Gaining too much weight during pregnancy may raise higher risks during delivery

Women with gestational diabetes who gain too much weight during pregnancy may face a higher risk of complications during delivery, according to new research from India. The study also identified a blood sugar marker that could help doctors recognize pregnancies at greater risk of delivering unusually large babies, potentially allowing closer monitoring and earlier intervention.

Gestational diabetes mellitus (GDM) develops during pregnancy and affects roughly 1 in 7 pregnant women globally, making it one of the most common pregnancy complications. While women typically manage the condition through diet and medication, doctors have lacked clear benchmarks for identifying which patients face the highest risks.

Researchers studied 148 women with gestational diabetes, examining two factors near the end of pregnancy: weight gained during pregnancy and glycated hemoglobin (HbA1c) level, a blood test reflecting average blood sugar levels over previous months.

Women who gained more weight than recommended were much more likely to deliver larger infants—babies whose birth weight exceeds that of 90% of newborns. Excessive weight gain was also associated with newborn complications including low blood sugar, jaundice, and breathing difficulties. Mothers with excessive weight gain were more likely to experience perineal tears during vaginal delivery.

Blood sugar control mattered independently. Women with HbA1c levels of 5.7% or higher were four times more likely to need cesarean sections or assisted vaginal delivery and three times more likely to deliver oversized babies.

Using statistical analysis, researchers identified an HbA1c level of 5.7% as the threshold that best predicted risk of delivering an unusually large infant.

Importantly, weight gain and blood sugar control appear to influence pregnancy outcomes in different ways. While elevated HbA1c was most strongly associated with operative delivery and large infant size, excessive weight gain showed even stronger associations with newborn complications.

The results highlight the importance of monitoring both blood sugar levels and pregnancy weight gain in women with gestational diabetes. However, the authors note that HbA1c measurements during pregnancy have limitations because normal physiological changes can affect test accuracy.

The research provides evidence that careful management of both factors may help improve outcomes for women with gestational diabetes and their newborns. The findings were published in Reproductive and Developmental Medicine.