An estimated 6 or 7 percent of pregnant women in the United States will develop gestational diabetes during pregnancy. That might not sound like much, but with 4 million births each year, that means about 250,000 annual cases of gestational diabetes – and these women have a seven-fold risk for developing Type 2 diabetes within a decade of delivery.
And yet, controversy still clouds gestational diabetes and how best to manage it, said Mark Landon, chair of the Department of Obstetrics and Gynecology at Ohio State University Wexner Medical Center.
Two large clinical trials, including one on which Landon was first author, have suggested that treating women with gestational diabetes – using dietary lifestyle interventions designed to keep blood sugar at normal levels for the vast majority of patients – significantly reduced the frequency of preeclampsia when compared to no treatment. Preeclampsia is a condition characterized by high blood pressure and protein in the urine after the 20th week of pregnancy. The only cure is delivery of the baby, but mild cases can be managed to delay delivery.
In spite of that, a meta-analysis published in 2010 stated that only modest evidence existed to show that treatment of gestational diabetes resulted in a benefit – but this analysis did not take preeclampsia into consideration.
Because gestational diabetes typically leads to larger babies, birth injuries also are a major concern – especially the possibility that a baby’s shoulder can get stuck in the birth canal, slowing delivery and creating conditions that could lead to shoulder nerve damage that lasts a lifetime.
Keeping the baby’s size in mind, practitioners must strike a balance between allowing a baby to develop safely to full term without letting it get so large that vaginal delivery becomes a dangerous prospect for mother and child. Waiting too long can lead to cesarean section, which carries its own complications.
A major analysis of 10 years of births appeared to suggest that 39 weeks gestation functioned as a good cutoff point to reduce risk of stillbirth or injury to the baby in mothers with gestational diabetes, though Landon said that seasoned physicians who have treated thousands of women with mild cases of gestational diabetes may not buy the argument that delivery is needed as early as 39 weeks.
Perhaps more useful to determine the optimal delivery time in the name of safety to mom and baby is estimating the baby’s weight. One national recommendation warned against prophylactic C-section in gestational diabetes pregnancies until a baby reached 4,500 grams, or just shy of 10 pounds, while a study suggested 4,250 grams, or 9.4 pounds, might be a more appropriate cutoff.
“Our approach continues to be for women who have never given birth vaginally is that we need to evaluate each woman carefully and individually … and consider a C-section even at a cutoff of 4,000 grams (8.8 pounds). This may seem like an aggressive approach, but given the flaws in the literature, it’s reasonable in clinical practice to do so,” Landon said.
Care for women with gestational diabetes does not stop in the delivery room, he noted, because of the elevated risk these women have of developing Type 2 diabetes and the need to plan these patients’ future pregnancies.
“We don’t do very well in this mission, and it is primarily a mission of those who provide obstetric care,” Landon noted, adding there are additional unknowns: “No one really knows what the appropriate time interval is for follow-up testing in women who screen normal for glucose in the immediate postpartum period but have a previous history of gestational diabetes.”
Landon co-authored a publication earlier this year calling on obstetricians to better promote women’s health after a diagnosis of gestational diabetes, including employing strategies that might reduce the frequency of diabetes and improve their overall general health.
Given the likelihood that children of women with gestational diabetes in some ethnic populations have increased risk for childhood obesity and metabolic syndrome, obstetricians have an opportunity to help break the cycle of diabetes, Landon suggested.
“Our responsibility doesn’t end in the delivery room. It extends to ensure the future health of that mother and her baby.”