Nature is wonderfully complex. During the second trimester of pregnancy, when the fetus is growing rapidly, hormones from the placenta begin to reduce the ability of the mother’s insulin to bind with insulin receptors. Because the mother’s insulin is consequently less able to shuttle glucose out of her bloodstream, the growing fetus is guaranteed a good supply of blood glucose.
To overcome this normal insulin resistance, which is comparable to that associated with type 2 diabetes, most pregnant women begin to produce about 1.5 to 2.5 times more insulin than before. Unfortunately, nearly fourteen percent of all pregnant women in the United States can’t muster enough insulin to compensate effectively. Because they don’t produce enough extra insulin to escort the glucose out of their bloodstream effectively, their blood glucose levels rise to the point that they develop gestational diabetes.
Because gestational diabetes develops in late pregnancy, after the baby’s body has been formed, it does not cause the birth defects that are sometimes caused by high glucose levels in early pregnancy. Still, there are serious problems associated with gestational diabetes. The mother’s extra blood glucose passes through the placenta, giving the baby a lot of excess glucose. To get rid of it, the the baby’s pancreas is forced to make extra insulin. Because of that extra insulin, the newborn may have a very low blood glucose level at birth. Furthermore, because the baby is getting more sugar than it needs to grow normally, the baby gets fat and becomes large, in some cases very large. (Consider the 19-pound baby boy recently born in Indonesia to a mother with diabetes.) These fatter and larger babies are subject to a higher likelihood of cesarean delivery and sometimes suffer damage to their shoulders as they are being born.. Their health future is less bright as well: Babies with excess insulin have a higher risk of becoming obese children and developing type 2 as adults.
Although severe gestational diabetes is always treated to avoid these complications, the question of whether mild gestational diabetes has deleterious effects on the baby has remained unanswered. As recently as 2008, the U.S. Preventive Services Task Force decided that there was not enough proof to justify pursuing treatment for mild gestational diabetes. Now, however, a study published in the October 1, 2009, issue of the New England Journal of Medicine, has shown that screening for and treating even mild gestational diabetes means fewer C-sections and other complications.
The study was a clinical trial carried out at 14 sites that are part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. In the trial, nearly 1000 women who were between 24 and 31 weeks pregnant were split into two groups. One group received gestational diabetes treatment that included diet changes, self-blood glucose monitoring, and exercise advice. Seven percent required insulin as well. The other group received no treatment.
The study found that mothers in the treatment group gave birth to half as many large babies (7.1 percent vs. 14.5 percent); produced far fewer fat babies (5.9 percent vs. 14.3 percent); and had fewer C-sections (26.9 percent vs. 33.8 percent). Mothers in the treatment group also gained less weight during pregnancy, had fewer premature babies, and were less likely to develop preeclampsia. (Preeclampsia, according to the Mayo Clinic, is a sudden rise in blood pressure that can result in premature delivery, disability, or death for mother and fetus, and often requires a C-section. It affects five to eight percent of pregnancies worldwide and is estimated to cause 50,000 to 76,000 maternal deaths every year.)
The researchers concluded that diagnosing and treating expectant mothers with even mild gestational diabetes benefits the lifelong health of both the mother and the child.
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