Babies’ Birthweight High, Despite Good Glycemic Control in Type 1 Diabetes, Small Study Finds

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By : Suvarna Sheth

A small U.S. study has found that women with type 1 diabetes still gave birth to larger babies despite good glycemic control using active diabetes management and continuous glucose monitoring.

In the study, researchers examined whether there were trimester-specific associations with glycemic variations, fetal growth, and birthweight involving pregnancies with type 1 diabetes.

The retrospective cohort study involved 41 pregnant women with type 1 diabetes and used the continuous glucose monitoring data to calculate glycemic variability over a 7-day interval each trimester.

Women maintained good glycemic control during pregnancy, with a mean HbA1c of 6.5% in the first trimester, 6.1% in the second trimester, and 6.4% in the third trimester. Even after this control, sixty-three percent of infants were large for gestational age.

“These data indicate that the prevalence of fetal overgrowth in type 1 diabetes remains alarmingly high, even with modern diabetes management,” indicates Dr. Bethany Mulla, from Beth Israel Deaconess Medical Center in Boston, Mass. in the study, published in Diabetes Technology and Therapeutics.

Researchers found that estimated fetal weight percentile and abdominal circumference percentile increased during pregnancy, which they say is consistent with accelerated prenatal growth.

They conclude that the occurrence of large for gestational age remains very high in contemporary U.S. women with type 1, despite the use of CGM and overall good glycemic control.

“Neither HbA1c nor glycemic variability predicted fetal overgrowth or birthweight,” the researchers report. “Since large for gestational age is a key driver of maternal and newborn complications in pregnancies with type 1 DM, our data emphasize the importance of investigating both glucose-dependent and glucose-independent underlying mechanisms,” the researchers conclude.

Many, however, could argue that studies of this size are not statistically significant and other variables such as race, BMI, pre-pregnancy glycemic control, duration of diseases, etc. should also be considered.

Mulla and colleagues also acknowledge that “placental factors, weight gain, obesity, or other factors had a greater influence on fetal growth than glucose variability.”