For pregnant women withdiabetes, some particular challenges exist for both mother and fetus. If the pregnant woman has diabetes as apre-existing disorder, it can causeearly labor,birth defects, and larger than average infants. Therefore, experts advise diabetics to maintainblood sugar level close to the normal range about 3 months before planning for pregnancy.[1]
Whentype 1 diabetes mellitus ortype 2 diabetes mellitus is pre-existing, planning in advance is emphasized if one wants to become pregnant, and stringent blood glucose control is needed before getting pregnant.[1]
Pre-gestational diabetes can be classified asType 1 orType 2 depending on the physiological mechanism.Type 1 diabetes mellitus is anautoimmune disorder leading to destruction ofinsulin-producing cell in the pancreas;type 2 diabetes mellitus is associated with obesity and results from a combination of insulin resistance and insufficient insulin production. Upon becoming pregnant, theplacenta produceshuman placental lactogen (HPL), a hormone withcounter-regulatory actions leading to increased blood glucose levels.[2] In combination with pre-existing diabetes, thesematernal physiological changes can lead to dangerously high blood glucose levels. This is significant because theconsequences of poorglycemic control are more severe during pregnancy compared to non-pregnant states.
The negative effects of pregestational diabetes are due to high blood sugar and insulin levels primarily during the first trimester of pregnancy (in contrast togestational diabetes, which can lead to fetal complications during the second and third trimesters). Since this period is when many of the major internal structures and organs of the fetus are developed, pre-existing diabetes can lead to congenital abnormalities. These include abnormal development of the heart and the central nervous system (brain and spinal cord). Strong correlations have been reported between diabetes andsacral agenesis,holoprosencephaly, and longitudinal limb deficiency.[3] With regards to the heart, increased likelihood oftruncus arteriosus,atrioventricular septal defect, and single ventricle complex has been found.[4] It is important to note that these complications are generally rare and can be averted with tight blood sugar control. Mild neurological and cognitive deficits in offspring — including increased symptoms ofADHD, impaired fine and gross motor skills, and impaired explicit memory performance — have been linked to pregestational type 1 diabetes and gestational diabetes.[5][6][7]
Pre-existing diabetes can also lead to complications in the neonate after birth, includingneonatal jaundice, hypoglycemia, andmacrosomia. Pregestational diabetes does not, however, increase the likelihood of diseases due to chromosomal alterations (e.g., Down Syndrome). Furthermore, miscarriages are also increased due to abnormal development in the early stages of pregnancy.[8]
Furthermore, when blood glucose is not controlled, shortly after birth, the infant's lungs may be underdeveloped, which can cause respiratory problems.[9] Hypoglycemia can occur after birth if the mother's blood sugar was high close to the time of delivery, which causes the baby to produce extra insulin of its own. A hyperglycemic maternal environment has also been associated with neonates who are at greater risk for the development of negative health outcomes such as future obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome.[10]
Blood glucose levels in pregnant women should be regulated as strictly as possible. During the first weeks of pregnancy, less insulin treatment is required due to tight blood sugar control as well as the extra glucose needed for the growing fetus.[11] At this timebasal andbolus insulin may need to be reduced to preventhypoglycemia. Frequent testing of blood sugar levels is recommended to maintain control. As the fetus grows and weight is gained throughout the pregnancy, the body produces more hormones, which may cause insulin resistance and the need for more insulin.[11] At this time, it is important for blood sugar levels to remain in range as the baby will produce more of its own insulin to cover its mother's higher blood sugar level, which can cause fetalmacrosomia.[12] During delivery, which is equivalent to exercise, insulin needs to be reduced again, or hyperglycemia can occur. After the baby is delivered and the days following, there are no more hormones from the placenta that demand more insulin; therefore, insulin demand is decreased and gradually returns to normal requirements.[9]
Diabetes mellitus may be effectively managed by appropriate meal planning, increased physical activity, and properly instituted insulin treatment. Some tips for controlling diabetes in pregnancy include:
TheNational Institute of Health and Care Excellence now recommends closed-loop insulin systems as an option for all women withtype 1 diabetes who are pregnant or planning pregnancy.[14][15][16]
In general,breastfeeding is good for the child even with a mother with diabetes mellitus. The child's risk for developing type 2 diabetes mellitus later in life may be lower if the baby was breast-fed. Breastfeeding also helps the child maintain a healthy body weight during infancy. However, thebreastmilk of mothers with diabetes has been demonstrated to have a different composition than that of non-diabetic mothers, containing elevated levels of glucose and insulin and decreasedpolyunsaturated fatty acids.[17] Although benefits of breast-feeding for the children of mothers with diabetes have been documented, ingestion of diabetic breast milk has also been linked to delayed language development on a dose-dependent basis.[17]
In some cases, pregnant women with diabetes may be encouraged to express and store theircolostrum during pregnancy, in case their blood sugar is too low for feeding the baby breast milk after birth.[18] There is no evidence on the safety or potential benefits when pregnant women with diabetes express and store breast milk before the baby's birth.[18]
The White classification, named afterPriscilla White,[19] who pioneered research on the effect of diabetes types on perinatal outcome, is widely used to assess maternal and fetal risk. It distinguishes between gestational diabetes (type A) and diabetes that existed before pregnancy (pregestational diabetes). These two groups are further subdivided according to their associated risks and management.[20]
There are 2 classes of gestational diabetes (diabetes that began during pregnancy):
The second group of diabetes, which existed before pregnancy, can be split up into these classes:
An early age of onset or long-standing disease comes with greater risks, hence the first three subtypes.
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