Pregnancy is divided into three trimesters of approximately three months each. Thefirst trimester includes conception, which is when the sperm fertilizes the egg. Thefertilized egg then travels down thefallopian tube and attaches to the inside of theuterus, where it begins to form theembryo andplacenta. During the first trimester, the possibility of miscarriage (natural death of embryo or fetus) is at its highest. Around the middle of the second trimester, movement of the fetus may be felt. At 28 weeks, more than 90% of babies cansurvive outside of the uterus ifprovided with high-quality medical care, though babies born at this time will likely experience serious health complications such as heart and respiratory problems and long-term intellectual and developmental disabilities.
William Hunter,Anatomia uteri humani gravidi tabulis illustrata, 1774
Associated terms for pregnancy aregravid andparous.Gravidus andgravid come from theLatin word meaning "heavy" and a pregnant female is sometimes referred to as agravida.[19]Gravidity refers to the number of times that a female has been pregnant. Similarly, the termparity is used for the number of times that a female carries a pregnancy to aviable stage.[20]Twins and other multiple births are counted as one pregnancy and birth.
A woman who has never been pregnant is referred to as anulligravida. A woman who is (or has been only) pregnant for the first time is referred to as aprimigravida,[21] and a woman in subsequent pregnancies as amultigravida or asmultiparous.[19][22] Therefore, during a second pregnancy a woman would be described asgravida 2, para 1 and upon live delivery asgravida 2, para 2. In-progress pregnancies,abortions,miscarriages and/orstillbirths account for parity values being less than the gravida number. Women who have never carried a pregnancy more than 20 weeks are referred to asnulliparous.[23]
A pregnancy is consideredterm at 37 weeks of gestation. It ispreterm if less than 37 weeks andpost-term at or beyond 42 weeks of gestation. The American College of Obstetricians and Gynecologists have recommended further division withearly term 37 weeks up to 39 weeks,full term 39 weeks up to 41 weeks, andlate term 41 weeks up to 42 weeks.[24] The termspreterm andpost-term have largely replaced earlier terms ofpremature andpostmature.Preterm andpostterm are defined above, whereaspremature andpostmature have historical meaning and relate more to the infant's size and state of development rather than to the stage of pregnancy.[25][26]
Melasma: pigment changes to the face due to pregnancyIn the later part of pregnancy, the uterus takes up much of the abdomen.
Each person's pregnancy can be different and many women do not experience all of the common signs and symptoms.[29] The usualsigns and symptoms of pregnancy do not significantly interfere withactivities of daily living or pose a health-threat to themother or baby.[29] Complications during pregnancy can cause other more severe symptoms, such as those associated withanemia.
Early signs and symptoms of pregnancy may include:[30]
Tiredness or fatigue (one of the most common symptoms)
Varicose veins. Common complaint caused by relaxation of the venoussmooth muscle and increased intravascular pressure.
Hemorrhoids (piles). Swollenveins at or inside the anal area. Caused by impaired venous return, straining associated with constipation, or increased intra-abdominal pressure in later pregnancy.[32]
Thechronology of pregnancy is, unless otherwise specified, generally given asgestational age, where the starting point is the beginning of the woman'slast menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. This model means that the woman is counted as being "pregnant" two weeks beforeconception and three weeks beforeimplantation. Sometimes, timing may also use thefertilization age, which is the age of the embryo since conception.
Earlyobstetric ultrasound, comparing the size of anembryo orfetus to that of areference group of pregnancies of known gestational age (such as calculated from last menstrual periods), and using the mean gestational age of other embryos or fetuses of the same size. If the gestational age as calculated from an early ultrasound is contradictory to the one calculated directly from the last menstrual period, it is still the one from the early ultrasound that is used for the rest of the pregnancy.[35]
Pregnancy is divided into three trimesters, each lasting for approximately three months.[4] The exact length of each trimester can vary between sources.
Thefirst trimester begins with the start of gestational age as described above, that is, the beginning of week 1, or 0 weeks + 0 days of gestational age (GA). It ends at week 12 (11 weeks + 6 days of GA)[4] or end of week 14 (13 weeks + 6 days of GA).[37]
Thesecond trimester is defined as starting, between the beginning of week 13 (12 weeks +0 days of GA)[4] and beginning of week 15 (14 weeks + 0 days of GA).[37] It ends at the end of week 27 (26 weeks + 6 days of GA)[37] or end of week 28 (27 weeks + 6 days of GA).[4]
Thethird trimester is defined as starting, between the beginning of week 28 (27 weeks + 0 days of GA)[37] or beginning of week 29 (28 weeks + 0 days of GA).[4] It lasts untilchildbirth.
Timeline of pregnancy, including (from top to bottom): Trimesters, embryo/fetus development,gestational age in weeks and months, viability and maturity stages
Estimation of due date
Distribution ofgestational age at childbirth among singleton live births, given both when gestational age is estimated by first trimester ultrasound and directly by last menstrual period.[38] Roughly 80% of births occur between 37 and 41 weeks of gestational age.
Determination of which time point is to be used asorigin forgestational age, as described in the section above.
Adding the estimated gestational age at childbirth to the above time point. Childbirth on average occurs at a gestational age of 280 days (40 weeks), which is therefore often used as a standard estimation for individual pregnancies.[39] However, alternative durations as well as more individualized methods have also been suggested.
Early-term: 37 weeks and 0 days through 38 weeks and 6 days
Full-term: 39 weeks and 0 days through 40 weeks and 6 days
Late-term: 41 weeks and 0 days through 41 weeks and 6 days
Post-term: greater than or equal to 42 weeks and 0 days
Naegele's rule is a standard way of calculating the due date for a pregnancy when assuming a gestational age of 280 days at childbirth. The rule estimates the expected date of delivery (EDD) by adding a year, subtracting three months, and adding seven days to the origin of gestational age. Alternatively there aremobile apps, which essentially always give consistent estimations compared to each other and correct forleap year, while pregnancy wheels made of paper can differ from each other by 7 days and generally do not correct for leap year.[41]
Furthermore, actual childbirth has only a certain probability of occurring within the limits of the estimated due date. A study of singleton live births came to the result that childbirth has astandard deviation of 14 days when gestational age is estimated by first trimesterultrasound, and 16 days when estimated directly by last menstrual period.[38]
Fertility andfecundity are the respective capacities tofertilize and establish a clinical pregnancy and have a live birth.Infertility is an impaired ability to establish a clinical pregnancy andsterility is the permanent inability to establish a clinical pregnancy.[42]
Fertilization (conception) is sometimes used as the initiation of pregnancy, with the derived age being termedfertilization age. Fertilization usually occurs about two weeks before thenext expected menstrual period.
A third point in time is also considered by some people to be the true beginning of a pregnancy: This is time of implantation, when the future fetus attaches to the lining of the uterus. This is about a week to ten days after fertilization.[45]
The sperm and the egg cell, which has been released from one of the female's twoovaries, unite in one of the twofallopian tubes. The fertilized egg, known as azygote, then moves toward the uterus, a journey that can take up to a week to complete. Cell division begins approximately 24 to 36 hours after the female and male cells unite. Cell division continues at a rapid rate and the cells then develop into what is known as ablastocyst. The blastocyst arrives at the uterus and attaches to the uterine wall, a process known asimplantation.
The development of the mass of cells that will become the infant is calledembryogenesis during the first approximately ten weeks of gestation. During this time, cells begin to differentiate into the various body systems. The basic outlines of the organ, body, and nervous systems are established. By the end of the embryonic stage, the beginnings of features such as fingers, eyes, mouth, and ears become visible. Also during this time, there is development of structures important to the support of the embryo, including theplacenta andumbilical cord. The placenta connects the developing embryo to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. The umbilical cord is the connecting cord from the embryo or fetus to the placenta.
After about ten weeks of gestational age—which is the same as eight weeks after conception—the embryo becomes known as afetus.[46] At the beginning of the fetal stage, the risk of miscarriage decreases sharply.[47] At this stage, a fetus is about 30 mm (1.2 inches) in length, the heartbeat is seen via ultrasound, and the fetus makes involuntary motions.[48] During continued fetal development, the early body systems, and structures that were established in the embryonic stage continue to develop. Sex organs begin to appear during the third month of gestation. The fetus continues to grow in both weight and length, although the majority of the physical growth occurs in the last weeks of pregnancy.
Electricalbrain activity is first detected at the end of week 5 of gestation, but as inbrain-dead patients, it is primitive neural activity rather than the beginning of conscious brain activity. Synapses do not begin to form until week 17.[49] Neural connections between thesensory cortex andthalamus develop as early as 24 weeks' gestational age, but the first evidence of their function does not occur until around 30 weeks, when minimalconsciousness,dreaming, and the ability to feel pain emerges.[50]
Although the fetus begins to move during the first trimester, it is not until the second trimester that movement, known asquickening, can be felt. This typically happens in the fourth month, more specifically in the 20th to 21st week, or by the 19th week if the woman has been pregnant before. It is common for some women not to feel the fetus move until much later. During the second trimester, when the body size changes,maternity clothes may be worn.
Embryo at 4 weeks after fertilization (gestational age of 6 weeks)
Fetus at 8 weeks after fertilization (gestational age of 10 weeks)
Fetus at 18 weeks after fertilization (gestational age of 20 weeks)
Fetus at 38 weeks after fertilization (gestational age of 40 weeks)
Relative size in 1st month (simplified illustration)
Relative size in 3rd month (simplified illustration)
Relative size in 5th month (simplified illustration)
Relative size in 9th month (simplified illustration)
Maternal changes
Theuterus expands making up a larger and larger portion of the abdomen. During the final stages of gestation the uterus may drop to a lower position.
End of second trimester + 2 weeks (26 weeks of pregnancy)
The fetus isgenetically different from its mother and can therefore be viewed as an unusually successfulallograft.[53] The main reason for this success is increasedimmune tolerance during pregnancy,[54] which prevents the mother's body from mounting animmune system response against certain triggers.[53]
During the second trimester, most women feel more energized and put on weight as the symptoms ofmorning sickness subside. They begin to feel regularfetal movements, which can become strong and even disruptive.[citation needed]
Final weight gain takes place during the third trimester; this is the most weight gain throughout the pregnancy. The woman's abdomen will transform in shape as the fetus turns in a downward position ready for birth. The woman'snavel will sometimes become convex, "popping" out, due to the expandingabdomen. The uterus, the muscular organ that holds the developing fetus, can expand up to 20 times its normal size during pregnancy.
Head engagement, also called "lightening" or "dropping", occurs as the fetal head descends into acephalic presentation. While it relieves pressure on the upper abdomen and gives a renewed ease in breathing, it also severely reduces bladder capacity, resulting in a need tovoid more frequently, and increases pressure on the pelvic floor and the rectum. It is not possible to predict when lightening will occur. In a first pregnancy it may happen a few weeks before the due date, though it may happen later or even not until labor begins, as is typical with subsequent pregnancies.[58]
It is during the third trimester that maternal activity and sleep positions may affectfetal development due to restrictedblood flow. For instance, the enlarged uterus may impede blood flow by compressing thevena cava when lying flat, a condition that can be relieved by lying on the left side.[59]
Childbirth, referred to as labor and delivery in the medical field, is the process whereby an infant is born.[60]
A woman is considered to be in labor when she begins experiencing regular uterine contractions, accompanied by changes of her cervix—primarily effacement and dilation. While childbirth is widely experienced as painful, some women do report painless labors, while others find that concentrating on the birth helps to quicken labor and lessen the sensations. Most births are successful vaginal births, but sometimes complications arise and a woman may undergo acesarean section.
During the time immediately after birth, both the mother and thebaby are hormonally cued to bond, the mother through the release ofoxytocin, a hormone also released duringbreastfeeding. Studies show that skin-to-skin contact between a mother and her newborn immediately after birth is beneficial for both the mother and baby. A review done by theWorld Health Organization found that skin-to-skin contact between mothers and babies after birth reduces crying, improves mother–infant interaction, and helps mothers to breastfeed successfully. They recommend thatneonates be allowed to bond with the mother during their first two hours after birth, the period that they tend to be more alert than in the following hours of early life.[61]
In the idealchildbirth, labor begins on its own when a woman is "at term".[17]Events before completion of 37 weeks are considered preterm.[62]Preterm birth is associated with a range of complications and should be avoided if possible.[64]
Sometimes if a woman'swater breaks or she hascontractions before 39 weeks, birth is unavoidable.[63] However, spontaneous birth after 37 weeks is considered term and is not associated with the same risks of a preterm birth.[60] Planned birth before 39 weeks bycaesarean section orlabor induction, although "at term", results in an increased risk of complications.[65] This is from factors includingunderdeveloped lungs of newborns, infection due to underdeveloped immune system, feeding problems due to underdeveloped brain, andjaundice from underdeveloped liver.[66]
Babies born between 39 and 41 weeks' gestation have better outcomes than babies born either before or after this range.[63] This special time period is called "full term".[63] Whenever possible, waiting for labor to begin on its own in this time period is best for the health of the mother and baby.[17] The decision to perform an induction must be made after weighing the risks and benefits, but is safer after 39 weeks.[17]
Events after 42 weeks are consideredpostterm.[63] When a pregnancy exceeds 42 weeks, the risk of complications for both the woman and the fetus increases significantly.[67][68] Therefore, in an otherwise uncomplicated pregnancy, obstetricians usually prefer to induce labor at some stage between 41 and 42 weeks.[69]
Thepostpartum period also referred to as thepuerperium, is the postnatal period that begins immediately after delivery and extends for about six weeks.[60] During this period, the mother's body begins the return to pre-pregnancy conditions that includes changes in hormone levels and uterus size.[60]
Diagnosis
The beginning of pregnancy may be detected either based on symptoms by the woman herself, or by usingpregnancy tests. However, an important condition with serious health implications that is quite common is thedenial of pregnancy by the pregnant woman. About 1 in 475 denials will last until around the 20th week of pregnancy. The proportion of cases of denial, persisting until delivery is about 1 in 2500.[70] Conversely, some non-pregnant women have a very strong belief that they are pregnant along with some of the physical changes. This condition is known as afalse pregnancy.[71]
Most pregnant women experience a number of symptoms,[72] which can signify pregnancy. A number of earlymedical signs are associated with pregnancy.[73][74] These signs include:
Pregnancy detection can be accomplished using one or more variouspregnancy tests,[76] which detect hormones generated by the newly formedplacenta, serving asbiomarkers of pregnancy.[77] Blood and urine tests can detect pregnancy by 11 and 14 days, respectively, after fertilization.[78][79] Blood pregnancy tests are moresensitive than urine tests (giving fewer false negatives).[80] Home pregnancy tests are urine tests, and normally detect a pregnancy 12 to 15 days after fertilization.[81] A quantitative blood test can determine approximately the date the embryo was fertilized becausehCG levels double every 36 to 72 hours before 8 weeks' gestation.[60][79] A single test ofprogesterone levels can also help determine how likely a fetus will survive in those with athreatened miscarriage (bleeding in early pregnancy), but only if the ultrasound result was inconclusive.[82]
Flowchart showing the recommended weight limits for lifting at work during pregnancy as a function of lifting frequency, weeks of gestation, and the position of the lifted object relative to the lifter's body.[86][87]
Pre-conception counseling is care that is provided to a woman or couple to discuss conception, pregnancy, current health issues and recommendations for the period before pregnancy.[88]
Prenatal medical care is the medical and nursing care recommended for women during pregnancy, time intervals and exact goals of each visit differ by country.[89] Women who are high risk have better outcomes if they are seen regularly and frequently by a medical professional than women who are low risk.[90] A woman can be labeled as high risk for different reasons including previous complications in pregnancy, complications in the current pregnancy, current medical diseases, or social issues.[91][92]
The aim of good prenatal care is prevention, early identification, and treatment of any medical complications.[93] A basic prenatal visit consists of measurement of blood pressure,fundal height, weight and fetal heart rate, checking for symptoms of labor, and guidance for what to expect next.[88]
Nutrition during pregnancy is important to ensure healthy growth of the fetus.[16] Nutrition during pregnancy is different from the non-pregnant state.[16] There are increased energy requirements and specific micronutrient requirements.[16] Women benefit from education to encourage a balanced energy and protein intake during pregnancy.[94] Some women may need professional medical advice if their diet is affected by medical conditions, food allergies, or specific religious/ ethical beliefs.[95] Further studies are needed to access the effect of dietary advice to preventgestational diabetes, although low quality evidence suggests some benefit.[96] Adequate periconceptional (time before and right after conception)folic acid (also called folate or Vitamin B9) intake has been shown to decrease the risk of fetal neural tube defects, such asspina bifida.[97] L-methylfolate, the bioavailable form of folate is also considered acceptable to take. L-methylfolate is best used by the 40% to 60% of the population with genetic polymorphisms that reduce or impair conversion of folic acid into its active form.[98] The neural tube develops during the first 28 days of pregnancy, a urine pregnancy test is not usually positive until 14 days post-conception, explaining the necessity to guarantee adequate folate intake before conception.[81][99] Folate is abundant ingreen leafy vegetables,legumes, andcitrus.[100] In the United States and Canada, most wheat products (flour, noodles) are fortified with folic acid.[101]
Weight gain
Measurement of the belly being performed by a pregnant woman during her pregnancy
The amount of healthy weight gain during a pregnancy varies.[102] Weight gain is related to the weight of the baby, the placenta, extra circulatory fluid, larger tissues, and fat and protein stores.[16] Most needed weight gain occurs later in pregnancy.[103]
TheInstitute of Medicine recommends an overall pregnancy weight gain for those of normal weight (body mass index of 18.5–24.9), of 11.3–15.9 kg (25–35 pounds) having a singleton pregnancy.[104] Women who are underweight (BMI of less than 18.5), should gain between 12.7 and 18 kg (28–40 lb), while those who areoverweight (BMI of 25–29.9) are advised to gain between 6.8 and 11.3 kg (15–25 lb) and those who areobese (BMI ≥ 30) should gain between 5–9 kg (11–20 lb).[105] These values reference the expectations for a term pregnancy.
During pregnancy, insufficient or excessive weight gain can compromise the health of the mother and fetus.[103] The most effective intervention for weight gain in underweight women is not clear.[103] Being or becoming overweight in pregnancy increases the risk of complications for mother and fetus, includingcesarean section,gestational hypertension,pre-eclampsia,macrosomia andshoulder dystocia.[102] Excessive weight gain can make losing weight after the pregnancy difficult.[102][106] Some of these complications are risk factors forstroke.[107]
Around 50% of women of childbearing age in developed countries like the United Kingdom are overweight or obese before pregnancy.[106] Diet modification is the most effective way to reduce weight gain and associated risks in pregnancy.[106]
Drugs used during pregnancy can have temporary or permanent effects on the fetus.[108] Anything (including drugs) that can cause permanent deformities in the fetus are labeled asteratogens.[109] In the U.S., drugs were classified into categories A, B, C, D and X based on theFood and Drug Administration (FDA) rating system to provide therapeutic guidance based on potential benefits and fetal risks.[110] Drugs, including somemultivitamins, that have demonstrated no fetal risks after controlled studies in humans are classified as Category A.[108] On the other hand, drugs likethalidomide with proven fetal risks that outweigh all benefits are classified as Category X.[108]
Alcoholic drinks consumed during pregnancy can cause one or morefetal alcohol spectrum disorders.[60] According to theCDC, there is no known safe amount of alcohol during pregnancy and no safe time to drink during pregnancy, including before a woman knows that she is pregnant.[111]
A video describing research onN95 respirator use during advanced pregnancy
Intrauterine exposure toenvironmental toxins in pregnancy has the potential to cause adverse effects onprenatal development, and to causepregnancy complications.[60] Air pollution has been associated with low birth weight infants.[117] Conditions of particular severity in pregnancy includemercury poisoning andlead poisoning.[60] To minimize exposure to environmental toxins, the American College of Nurse-Midwives recommends: checking whether the home haslead paint, washing all freshfruits andvegetables thoroughly and buyingorganic produce, and avoiding cleaning products labeled "toxic" or any product with a warning on the label.[118]
Pregnant women can also be exposed totoxins in the workplace, including airborne particles. The effects of wearing anN95 filtering facepiece respirator are similar for pregnant women as for non-pregnant women, and wearing a respirator for one hour does not affect the fetal heart rate.[119]
Death by violence
Pregnant women or those who have recently given birth in the U.S. aremore likely to be murdered than to die from obstetric causes. These homicides are a combination of intimate partner violence and firearms. Health authorities have called the violence "a health emergency for pregnant women", but say that pregnancy-related homicides are preventable if healthcare providers identify those women at risk and offer assistance to them.[120][121][122]
Most women can continue to engage in sexual activity, includingsexual intercourse, throughout pregnancy.[123] Research suggests that during pregnancy both sexual desire and frequency of sexual relations decrease during the first and third trimester, with a rise during the second trimester.[124][125][126][127] Sex during pregnancy is a low-risk behavior except when the healthcare provider advises that sexual intercourse be avoided for particular medical reasons.[123] For a healthy pregnant woman, there is no single safe or right way to have sex during pregnancy.[123]
Exercise
A pregnant woman and her colleague returning from fishing, Gurara River bridge,Kachia, Nigeria
Regularaerobic exercise during pregnancy appears to improve (or maintain) physical fitness.[128]Physical exercise during pregnancy appears to decrease the need forC-section[129] and reduce time in labor,[130] and even vigorous exercise carries no significant risks to babies[131] while providing significant health benefits to the mother. Studies show that performing light moderate intensity and strength exercises while pregnant does not harm the mother’s cardiovascular system and may limit excessive weight gain.[132][additional citation(s) needed]
The American College of Sports and Medicine recommends pregnant women should participate in at least 150 minutes/week of moderate exercise.[133] These forms of exercise should avoid heavy lifting, hot temperatures, and high impact sports. The Clinical Practice Obstetrics Committee of Canada recommends that "All women without contraindications should be encouraged to participate in aerobic and strength-conditioning exercises as part of a healthy lifestyle during their pregnancy".[134] Although an upper level of safe exercise intensity has not been established, women who were regular exercisers before pregnancy and who have uncomplicated pregnancies should be able to engage in high intensity exercise programs without a higher risk of prematurity, lower birth weight, or gestational weight gain.[131] In general, participation in a wide range of recreational activities appears to be safe, with the avoidance of those with a high risk of falling such as horseback riding or skiing or those that carry a risk of abdominal trauma, such as soccer or hockey.[135]
Bed rest, outside of research studies, is not recommended as there is potential harm and no evidence of benefit.[136]
High intensity exercise
During pregnancy, women can experience a loss of postural stability, pelvic incontinence, back pain, and fatigue, among other symptoms.[citation needed] Resistance training has been found to reduce pregnancy symptoms and reduce postpartum complications.[citation needed] Provided that women also regularly participate in low-impact training, strength training can improve pelvic girdle pain severity postpartum.[137] When incorporating exercises that focus on pelvic muscle strength, they can help reduce pain and stress urinary incontinence.[137]
Engaging in regular exercise and physical activity has been shown to be beneficial during pregnancy. Acute bouts ofhigh intensity interval training can help decrease the risks of health complications associated with pregnancy, maintain a healthy body fat percentage during pregnancy, as well as improve overall well-being.[138] Pregnant women who participated in high intensity interval training have been shown to undergo physical improvements in body composition after intervention as well as show general improvement in cardiorespiratory fitness and exercise tolerance.[139] Taking part in this style of exercise, similarly to moderate intensity continuous training, has also been shown to improve glycemic response and insulin sensitivity.[140] There are specific concerns to be avoided with exercise during pregnancy such as overheating, fall-risk, and remaining in a supine position for an extended period of time. Inexperienced individuals new to high-intensity interval training could potentially increase their risk for negative conditions associated with hypertension, such as pre-eclampsia.[141]
It has been suggested thatshift work and exposure to bright light at night should be avoided at least during the last trimester of pregnancy to decrease the risk of psychological and behavioral problems in the newborn.[142]
Stress
The children of women who had high stress levels during pregnancy are slightly more likely to haveexternalizing behavioral problems such as impulsivity.[139] The behavioral effect was most pronounced during early childhood.[139]
The increased levels ofprogesterone andestrogen during pregnancy makegingivitis more likely; thegums become edematous, red in colour, and tend to bleed.[143] Also apyogenic granuloma or "pregnancy tumor", is commonly seen on the labial surface of the papilla. Lesions can be treated by local debridement or deep incision depending on their size, and by following adequateoral hygiene measures.[144] There have been suggestions that severeperiodontitis may increase the risk of havingpreterm birth andlow birth weight; however, a Cochrane review found insufficient evidence to determine ifperiodontitis can develop adverse birth outcomes.[145]
Flying
In low risk pregnancies, most health care providers approve flying until about 36 weeks of gestational age.[146] Most airlines allow pregnant women to fly short distances at less than 36 weeks, and long distances at less than 32 weeks.[147] Many airlines require a doctor's note that approves flying, especially at over 28 weeks.[147] During flights, the risk ofdeep vein thrombosis is decreased by getting up and walking occasionally, as well as by avoiding dehydration. The exposure to cosmic radiation is negligible for most travelers. For pregnant women, even the longest intercontinental fight would expose them less than 15% of both theNCRPM andICRP limit.[148][147]Full body scanners do not use ionizing radiation, and are safe in pregnancy.[149]
To prepare for the birth of the baby, health care providers recommend that parents attend antenatal classes during the third trimester of pregnancy. Classes include information about the process of labor and birth and the various kinds of births, including both vaginal andcaesarean delivery, the use of forceps, and other interventions that may be needed to safely deliver the infant. Types of pain relief, including relaxation techniques, are discussed. Partners or others who may plan to support a woman during her labor and delivery learn how to assist in the birth.[citation needed]
It is also suggested that a birth plan be written at this time. A birth plan is a written statement that outlines the desires of the mother during labor and delivery of the baby. Discussing the birth plan with the midwife or other care provider gives parents a chance to ask questions and learn more about the process of labour.[150]
In 1991 theWHO launched theBaby-Friendly Hospital Initiative, a global program that recognizes birthing centers and hospitals that offer optimal levels of care for giving birth. Facilities that have been certified as "Baby Friendly" accept visits from expecting parents to familiarize them with the facility and the staff.[151]
Pruritic urticarial papules and plaques of pregnancy (PUPPP), a skin disease that develops around the 32nd week. Signs are red plaques, papules, and itchiness around the belly button that then spreads all over the body except for the inside of hands and face.
Miscarriage is the most common complication of early pregnancy. It is defined as the loss of an embryo or fetus before it is able to survive independently. The most common symptom of miscarriage is vaginal bleeding with or without pain. The miscarriage may be evidenced by a clot-like material passing through and out of the vagina.[157] About 80% of miscarriages occur in the first 12 weeks of pregnancy. The underlying cause in about half of cases involves chromosomal abnormalities.[158]
Stillbirth is defined as fetal death after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without signs of life. Each year about 21,000 babies are stillborn in the U.S.[159] Sadness, anxiety, and guilt may occur after a miscarriage or a stillbirth. Emotional support may help with processing the loss.[160] Fathers may experience grief over the loss as well. A large study found that there is a need to increase the accessibility of support services available for fathers.[161]
A pregnant woman may have apre-existing disease, which is not directly caused by the pregnancy, but may causecomplications to develop that include a potential risk to the pregnancy; or a disease may develop during pregnancy.
Thyroid disease in pregnancy can, if uncorrected, cause adverse effects on fetal and maternal well-being. The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affectneurointellectual development in the early life of the child. Demand for thyroid hormones is increased during pregnancy, which may cause a previously unnoticed thyroid disorder to worsen.
Hypercoagulability in pregnancy is the propensity of pregnant women to developthrombosis (blood clots). Pregnancy itself is a factor ofhypercoagulability (pregnancy-induced hypercoagulability), as a physiologically adaptive mechanism to preventpostpartum bleeding.[165] However, in combination with an underlying hypercoagulable state, the risk of thrombosis or embolism may become substantial.[165]
An abortion is the termination of an embryo or fetus via medical method. It is usually done within the first trimester, sometimes in the second, and rarely in the third. Reasons forpregnancies being undesired are broad.[166] Many jurisdictions restrict or prohibit abortion, withrape being the most legally permissible exception.[167]
Family planning, as well as the availability and use ofcontraception, along with increasedcomprehensive sex education, has enabled many to prevent pregnancies when they are not desired. Schemes and funding to support education and the means to prevent pregnancies when they are not intended have been instrumental and are part of the third of theSustainable Development Goals (SDGs) advanced by theUnited Nations.[168]
CT scanning (volume rendered in this case) confers aradiation dose to the developing fetus.A pregnant woman undergoing anultrasound. Ultrasound is used to check on the growth and development of the fetus.
About 213 million pregnancies occurred in 2012 of which 190 million were in thedeveloping world and 23 million were in the developed world.[11] This is about 133 pregnancies per 1,000 women aged 15 to 44.[11] About 10% to 15% of recognized pregnancies end in miscarriage.[2] Globally, 44% of pregnancies areunplanned. Over half (56%) of unplanned pregnancies are aborted. In countries whereabortion is prohibited, or only carried out in circumstances where the mother's life is at risk, 48% of unplanned pregnancies areaborted illegally. Compared to the rate in countries where abortion is legal, at 69%.[27]
Of pregnancies in 2012, 120 million occurred in Asia, 54 million in Africa, 19 million in Europe, 18 million in Latin America and the Caribbean, 7 million in North America, and 1 million inOceania.[11] Pregnancy rates are 140 per 1000 women of childbearing age in the developing world and 94 per 1000 in the developed world.[11]
The rate of pregnancy, as well as the ages at which it occurs, differ by country and region. It is influenced by a number of factors, such as cultural, social and religious norms; access to contraception; and rates of education. Thetotal fertility rate (TFR) in 2013 was estimated to be highest inNiger (7.03 children/woman) and lowest inSingapore (0.79 children/woman).[170]
In Europe, the average childbearing age has been rising continuously for some time. In Western, Northern, and Southern Europe, first-time mothers are on average 26 to 29 years old, up from 23 to 25 years at the start of the 1970s. In a number of European countries (Spain), the mean age of women at first childbirth has crossed the 30-year threshold.
This process is not restricted to Europe. Asia, Japan and the United States are all seeing average age at first birth on the rise, and increasingly the process is spreading to countries in the developing world like China, Turkey and Iran. In the US, the average age of first childbirth was 25.4 in 2010.[171]
In the United States and United Kingdom, 40% of pregnancies areunplanned, and between a quarter and half of those unplanned pregnancies wereunwanted pregnancies.[172][173]
In the US, a woman's educational attainment and her marital status are historically correlated with childbearing: the percentage of women unmarried at the time of first birth drops with increasing educational level. Three studies conducted between 2015 and 2018 indicate a large fraction (~80%) of women without ahigh school diploma or local equivalent in the US are unmarried at the time of their first birth. By contrast, the same studies indicated fewer women with a bachelor's degree or higher (~24%) have their first child while unmarried. However, this phenomenon also has a strong generational component: a 1996 study found 48.2% of US women without a bachelor's degree had their first child whilst unmarried, and only 4% of women with a bachelor's degree had their first child whilst unmarried. These studies indicate a rising trend for US women of all educational levels to be unmarried at the time of their first birth,[174] and thus a recent weakening of the correlation between educational attainment, marital status, and childbearing.
Many countries have various legal regulations in place to protect pregnant women and their children. Many countries have laws againstpregnancy discrimination.[175]
Maternity Protection Convention ensures that pregnant women are exempt from activities such as night shifts or carrying heavy stocks.Maternity leave typically provides paid leave from work during roughly the last trimester of pregnancy and for some time after birth. Notable extreme cases include Norway (8 months with full pay) and the United States (no paid leave at all except in some states).
In the United States, some actions that result in miscarriage or stillbirth, such as beating a pregnant woman, are considered crimes. One law that does so is the federalUnborn Victims of Violence Act. In 2014, the American state ofTennessee passed a law which allows prosecutors to charge a woman with criminal assault if she uses illegal drugs during her pregnancy and her fetus or newborn is harmed as a result.[176]
However, protections are not universal. InSingapore, theEmployment of Foreign Manpower Act forbids current and formerwork permit holders from becoming pregnant or giving birth in Singapore without prior permission.[177][178] Violation of the Act is punishable by a fine of up toS$10,000 (US$7300) anddeportation,[177][179] and until 2010, their employers would lose their $5,000 security bond.[180]
Teenage pregnancy is also known asadolescent pregnancy.[181] TheWHO defines adolescence as the period between the ages of 10 and 19 years.[182] Adolescents face higher health risks than women who give birth at age 20 to 24 and their infants are at a higher risk for preterm birth, low birth weight, and other severe neonatal conditions. Their children continue to face greater challenges, both behavioral and physical, throughout their lives. Teenage pregnancies are also related to social issues, includingsocial stigma, lower educational levels, and poverty.[183][181] Studies show that female adolescents are often in abusive relationships at the time of their conceiving.[184]
Nurse-Family Partnership (NFP) is a non-profit organization operating in the United States and the UK designed to serve the needs of low income young mothers who may have special needs in their first pregnancy. Each mother served is partnered with a registered nurse early in her pregnancy and receives ongoing nurse home visits that continue through her child's second birthday. NFP intervention has been associated with improvements in maternal health, child health, and economic security.[185][186]
Racial disparities
There are significant racial imbalances in pregnancy and neonatal care systems.[187] Midwifery guidance, treatment, and care have been related to better birth outcomes. Diminishing racial inequities in health is an increasingly large public health challenge in the United States. Despite the fact that average rates have decreased, data on neonatal mortality demonstrates that racial disparities have persisted and grown. The death rate for African American babies is nearly double that of white neonates. According to studies,congenital defects,SIDS,preterm birth, andlow birth weight are all more common among African American babies.[188]
Midwifery care has been linked to better birth and postpartum outcomes for both mother and child. It caters to the needs of the woman and provides competent, sympathetic care, and is essential for maternal health improvement. The presence of adoula, or birth assistant, during labor and delivery, has also been associated with improved levels of satisfaction with medical birth care. Providers recognized their profession from a historical standpoint, a link to African origins, the diaspora, and prevailing African American struggles. Providers participated in both direct clinical experience and activist involvement. Advocacy efforts aimed to enhance the number of minority birth attendants and to promote the benefits of woman-centered birth care to neglected areas.[188]
Transgender people have experienced significant advances in societal acceptance in recent years leaving many health professionals unprepared to provide quality care. A 2015 report suggests that "numbers of transgender individuals who are seeking family planning, fertility, and pregnancy services could certainly be quite large".Regardless of prior hormone replacement therapy treatments, the progression of pregnancy and birthing procedures fortransgender people who carry pregnancies are typically the same as those ofcisgender women.[189] However, transgender people may be subjected to discrimination, which can include a variety of negative social, emotional, and medical experiences, as pregnancy is regarded as an exclusively female activity. According to a study by theAmerican College of Obstetricians and Gynecologists, there is a lack of awareness, services, and medical assistance available to pregnant trans men.[190]
In most cultures, pregnant women have a special status in society and receive particularly gentle care.[191] At the same time, they are subject to expectations that may exert great psychological pressure, such as having to produce a son and heir. In many traditional societies, pregnancy must be preceded by marriage, on pain of ostracism of mother and(illegitimate) child.
Overall, pregnancy is accompanied by numerous customs that are often subject to ethnological research, often rooted intraditional medicine or religion. Thebaby shower is an example of a modern custom. Contrary tocommon misconception, women historically in theUnited States were not expected to seclude themselves during pregnancy, as was popularized byGone With the Wind.[192][193]
Pregnancy is an important topic insociology of the family. The prospective child may preliminarily be placed into numeroussocial roles. The parents' relationship and the relation between parents and their surroundings are also affected.
Abelly cast may be made during pregnancy as a keepsake.
Images of pregnant women, especially smallfigurines, were made in traditional cultures in many places and periods, though it is rarely one of the most common types of image. These include ceramic figures from somePre-Columbian cultures, and a few figures from most of the ancient Mediterranean cultures. Many of these seem to be connected withfertility. Identifying whether such figures are actually meant to show pregnancy is often a problem, as well as understanding their role in the culture concerned.
Among the oldest surviving examples of the depiction of pregnancy are prehistoric figurines found across much ofEurasia and collectively known asVenus figurines. Some of these appear to be pregnant.
Due to the important role of theMother of God inChristianity, the Western visual arts have a long tradition of depictions of pregnancy, especially in the biblical scene of theVisitation, and devotional images called aMadonna del Parto.[194]
The unhappy scene usually calledDiana and Callisto, showing the moment of discovery ofCallisto's forbidden pregnancy, is sometimes painted from the Renaissance onwards. Gradually, portraits of pregnant women began to appear, with a particular fashion for "pregnancy portraits" in elite portraiture of the years around 1600.
Pregnancy, and especially pregnancy of unmarried women, is also an important motif in literature. Notable examples includeThomas Hardy's 1891 novelTess of the d'Urbervilles and Goethe's 1808 playFaust.
^Lama Rimawi, MD (22 September 2006)."Premature Infant".Disease & Conditions Encyclopedia. Discovery Communications, LLC.Archived from the original on 19 January 2008. Retrieved16 January 2008.
^abHoffman CS, Messer LC, Mendola P, Savitz DA,Herring AH, Hartmann KE (November 2008). "Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester".Paediatric and Perinatal Epidemiology.22 (6):587–596.doi:10.1111/j.1365-3016.2008.00965.x.PMID19000297.
^Chambliss LR, Clark SL (February 2014). "Paper gestational age wheels are generally inaccurate".American Journal of Obstetrics and Gynecology.210 (2): 145.e1–145.e4.doi:10.1016/j.ajog.2013.09.013.PMID24036402.
"Women's Health InformationArchived 30 April 2007 at theWayback Machine", Hearthstone Communications Limited: "The risk of miscarriage decreases dramatically after the 8th week as the weeks go by." Retrieved 2007-04-22.
^abMor G, ed. (2006).Immunology of pregnancy. Medical intelligence unit. Georgetown, Tex. : New York: Landes Bioscience/Eurekah.com; Springer Science+Business Media. pp. 1–4.doi:10.1007/0-387-34944-8.ISBN978-0-387-34944-2.
^Campbell LA, Klocke RA (April 2001). "Implications for the pregnant patient".American Journal of Respiratory and Critical Care Medicine.163 (5):1051–1054.doi:10.1164/ajrccm.163.5.16353.PMID11316633.
^Qasim SM, Callan C, Choe JK (October 1996). "The predictive value of an initial serum beta human chorionic gonadotropin level for pregnancy outcome following in vitro fertilization".Journal of Assisted Reproduction and Genetics.13 (9):705–708.doi:10.1007/BF02066422.PMID8947817.S2CID36218409.
^ab"What is HCG?".American Pregnancy Association. 18 October 2021. Retrieved23 July 2023.
^abCole LA, Khanlian SA, Sutton JM, Davies S, Rayburn WF (January 2004). "Accuracy of home pregnancy tests at the time of missed menses".American Journal of Obstetrics and Gynecology.190 (1):100–105.doi:10.1016/j.ajog.2003.08.043.PMID14749643.
^Ota E, Hori H, Mori R, Tobe-Gai R, Farrar D (June 2015). "Antenatal dietary education and supplementation to increase energy and protein intake".The Cochrane Database of Systematic Reviews.2015 (6): CD000032.doi:10.1002/14651858.CD000032.pub3.PMID26031211.
^"| Choose MyPlate".Choose MyPlate. 29 April 2015.Archived from the original on 17 November 2015. Retrieved15 November 2015.
^Klusmann A, Heinrich B, Stöpler H, Gärtner J, Mayatepek E, Von Kries R (November 2005). "A decreasing rate of neural tube defects following the recommendations for periconceptional folic acid supplementation".Acta Paediatrica.94 (11):1538–1542.doi:10.1080/08035250500340396.PMID16303691.S2CID13506877.
^Stevenson RE, Allen WP, Pai GS, Best R, Seaver LH, Dean J, et al. (October 2000). "Decline in prevalence of neural tube defects in a high-risk region of the United States".Pediatrics.106 (4):677–683.doi:10.1542/peds.106.4.677.PMID11015508.S2CID39696556.
^Centers for Disease Control Prevention (CDC) (January 2008). "Use of supplements containing folic acid among women of childbearing age--United States, 2007".MMWR. Morbidity and Mortality Weekly Report.57 (1):5–8.PMID18185493.
^abcViswanathan M, Siega-Riz AM, Moos MK, et al. (May 2008)."Outcomes of Maternal Weight Gain".Evidence Report/Technology Assessment. Evidence Reports/Technology Assessments, No. 168 (168). Agency for Healthcare Research and Quality:1–223.PMC4781425.PMID18620471.Archived from the original on 28 May 2013. Retrieved23 June 2013.
^abcInstitute for Quality and Efficiency in Health Care."Weight gain in pregnancy".Fact sheet. Institute for Quality and Efficiency in Health Care.Archived from the original on 14 December 2013. Retrieved23 June 2013.
^Genetic Alliance, The New England Public Health Genetics Education Collaborative (17 February 2010)."Appendix A: Teratogens/Prenatal Substance Abuse".Understanding Genetics: A New England Guide for Patients and Health Professionals. Genetic Alliance.
^Martin R, Dombrowski SC (2008). "12. Air and Water Pollution".Prenatal exposures: psychological and educational consequences for children. New York: Springer.doi:10.1007/978-0-387-74398-1.ISBN978-0-387-74398-1.
^Reamy K, White SE, Daniell WC, Le Vine ES (June 1982). "Sexuality and pregnancy. A prospective study".The Journal of Reproductive Medicine.27 (6):321–327.PMID7120209.
^Malarewicz A, Szymkiewicz J, Rogala J (September 2006). "[Sexuality of pregnant women]".Ginekologia Polska (in Polish).77 (9):733–739.PMID17219804.
^Domenjoz I, Kayser B, Boulvain M (October 2014). "Effect of physical activity during pregnancy on mode of delivery".American Journal of Obstetrics and Gynecology.211 (4): 401.e1–401.11.doi:10.1016/j.ajog.2014.03.030.PMID24631706.
^Davies GA, Wolfe LA, Mottola MF, MacKinnon C, Arsenault MY, Bartellas E, et al. (June 2003). "Exercise in pregnancy and the postpartum period".Journal of Obstetrics and Gynaecology Canada.25 (6):516–529.doi:10.1016/s1701-2163(16)30313-9.PMID12806453.
^McCall CA, Grimes DA, Lyerly AD (June 2013). ""Therapeutic" bed rest in pregnancy: unethical and unsupported by data".Obstetrics and Gynecology.121 (6):1305–1308.doi:10.1097/aog.0b013e318293f12f.PMID23812466.
^Stewart DE, Vigod S (December 2016). "Postpartum Depression".The New England Journal of Medicine.375 (22):2177–2186.doi:10.1056/nejmcp1607649.PMID27959754.
^Saccone G, Berghella V, Sarno L, Maruotti GM, Cetin I, Greco L, et al. (February 2016). "Celiac disease and obstetric complications: a systematic review and metaanalysis".American Journal of Obstetrics and Gynecology.214 (2):225–234.doi:10.1016/j.ajog.2015.09.080.hdl:11369/330101.PMID26432464.
^abPage 264 in:Gresele, Paolo (2008).Platelets in hematologic and cardiovascular disorders: a clinical handbook. Cambridge, UK: Cambridge University Press.ISBN978-0-521-88115-9.
^abGuerra-Reyes L, Hamilton LJ (February 2017). "Racial disparities in birth care: Exploring the perceived role of African-American women providing midwifery care and birth support in the United States".Women and Birth.30 (1):e9 –e16.doi:10.1016/j.wombi.2016.06.004.PMID27364419.
.gif)
.svg)
