Gestational diabetes mellitus (GDM) is glucose intolerance that a pregnant woman, previously non-diabetic, develops during her pregnancy. This results in high blood sugar levels during her pregnancy period, which can have certain undesirable effects.
GDM can affect the mother and the baby in a number of ways and can have both short-term and long-term complications in both. The risks of these complications increase with higher blood glucose levels.
Complications in the fetus can extend to it even as a neonate, as a child and as an adult. However, proper control of diabetes considerably reduces the risks of these dangers.
Well controlled sugar levels throughout pregnancy may not cause any complications in the absence of other factors.
But, poorly controlled gestational diabetes increases the maternal risk of surgical interference during delivery, pre-eclampsia, and the development of diabetes type 2 later in life.
Preeclampsia: Hypertensive disorder
Preeclampsia risk increases with GDM in which the mother develops high blood pressure and presence of protein in urine after the 20th week of pregnancy.
A part of the risk is due to coexisting obesity, family history and increased age. But, besides these additional factors that increase the risk, GDM, per se, is considered an independent risk factor as well.
However, the exact mechanism involved in the association between insulin resistance and hypertensive disorders, is not yet clear.
Studies have documented a higher risk of hypertensive disorder in GDM women reaching as high as 17% versus 12% in non-diabetic women. The rate of pre-eclampsia is related to the severity of the diabetes and is diagnosed more in younger age more during the first pregnancy, in obese women and in those with a higher than normal weight gain during pregnancy.
Development of gestational diabetes during the second and third trimester can cause excessive growth of the baby (larger baby weighing 9 pounds or more). This is called macrosomia.
There is a positive relation established between increased maternal blood glucose and increase in the baby’s weight. This may increase the need for the baby to be delivered by cesarean section. The risk of cesarean is doubled in pregnancies with gestational diabetes.
Women with GDM who were being treated for the same remained at a higher risk for cesarean delivery of about 33%. In untreated women, the rate of C-section is higher. In the normal population, the rate of cesarean section is 17%.
Again, women with GDM are prone to higher risk of vaginal operative deliveries such as forceps-assisted delivery and vacuum-assisted delivery.
Post partum diabetes mellitus type 2 in women with h/o GDM
According to Mayo clinic, women with a history of gestational diabetes during their pregnancy and who reach their ideal body weight post delivery, less than 1 in 4 eventually develop type 2 diabetes.
Type 2 diabetes develops later in life in more women with h/o poorly controlled GDM. There are several risk factors that increase the GDM woman’s risk of developing postpartum diabetes.
- Ethnicity: African-American, Latino, Native American, Asian American, Pacific Islander are most susceptible to postpartum diabetes
- Higher age of delivery equal to or more than 33 to 35 years
- More number of children
- Family history of diabetes
- Early development of GDM at or before 22 to 24 weeks
- Severity of gestational diabetes
- Very high blood sugar levels during pregnancy and immediately postpartum
Untreated gestational diabetes increases the risk of fetal and neonatal complications such as congenital malformations, neonatal hypoglycemia, childhood obesity and diabetes later in life.
Early (preterm) birth
Maternal high blood sugar may increase risk of early labor and delivery of the baby before the due date.
Babies born early are at an increased risk of developing respiratory distress syndrome because the lungs are still not fully developed.
Development of maternal diabetes in early pregnancy can affect the baby’s development throughout pregnancy. It can cause birth defects which affect the major organs such as the brain and the heart. Risk of premature delivery, miscarriage and still birth is also greatly increased.
Injury during labor
If the larger baby is delivered vaginally, there is risk of shoulder damage to the baby. This is called shoulder dystocia in which during delivery the head emerges but the shoulder of the baby can get stuck in the birth canal and cause nerve injury to the shoulder of the baby and can also damage the birth canal of the mother.
If the pregnant mother with gestational diabetes has high blood sugar especially just before delivery, the baby can be born with low blood sugar levels at birth.
This is because the baby’s blood is having high insulin levels to fight the extra blood sugar flowing from the mother through the placenta.
After birth the high sugar blood supply has suddenly stopped while the baby’s insulin levels in the blood are still high. This causes the baby’s blood sugar to fall after birth.
Therefore, the baby’s blood sugar is checked after delivery and if necessary intravenous glucose is administered. This is done especially when the mother is known to have gestational diabetes.
Respiratory distress syndrome
As specified above, babies of mothers who have gestational diabetes often develop respiratory distress syndrome in which the babies find it difficult to breathe and may need help to breathe till their lungs develop fully and become mature. Neonatal intensive care admission may be necessary.
This can happen not only in babies born pre-term but also in those born full-term.
The baby may develop neonatal jaundice, which causes yellowish discoloration of the skin and the whites of the eyes. Though this is mostly harmless, proper monitoring is important.
A very large baby is at an increased risk of developing obesity later in life or even earlier during childhood, which again makes the baby prone to developing diabetes mellitus later in life.