How does pregnancy weight gain affect infant birth weight in type 1 diabetic mothers?

This study looked at the association between weight gain during pregnancy and baby birth weight in women with type 1 diabetes (T1D). This study concluded that higher weight gain was associated with higher birth weights, regardless of blood glucose levels in women with T1D.

Nearly half of babies born to women with T1D are born larger than normal. This is mainly due to the transfer of the mother’s glucose (sugar) to the baby through the placenta. The increased glucose lead to higher levels of insulin in the baby and increased growth. Infants that are born overweight are at increased risk of being overweight and of developing type 2 diabetes as adults.

Weight gain during pregnancy can increase the risk of high birth weights in all women. It is not clear whether excessive weight gain increases the risks for women with T1D.

This study evaluated the association between weight gain during pregnancy and infant birth weight in women with T1D. 

This study examined the records of 115 pregnant women with T1D. All women followed routine T1D pregnancy care programs and delivered at full term. HbA1c (average blood glucose levels over 3 months) and weight were measured at 2-week intervals throughout the pregnancies. Self-monitored glucose measurements were recommended 7 times daily. The women were categorized into 3 groups based on their pregnancy weight gain: excessive, appropriate and insufficient weight gain.

HbA1c levels were similar between weight groups.  Birth weight increased significantly with increased weight gain in the mother. Average birth weight for women with insufficient weight gain was 3295 g (7.25 lbs). Average birth weight for women who gained excessive weight was 3681 g (8.11 lbs). Pregnancy weight gain was associated with increased birth weight regardless of pre-pregnancy weight or HbA1c.

The study concluded that higher pregnancy weight gain in women with T1D was associated with increased baby birth weight independent of the mother’s glucose control.

The birth weight and height of the babies was measured, however, this did not take into consideration body composition (that is what percentage was fat, muscle or water). If baby skinfolds were measured this would allow body fat levels to be more appropriately assessed. 

Discuss appropriate weight gain levels during pregnancy with your doctor.