Higher Gestational Weight Gain Is Associated With Increasing Offspring Birth Weight Independent of Maternal Glycemic Control in Women With Type 1 Diabetes

OBJECTIVE We evaluate the association between gestational weight gain and offspring birth weight in singleton term pregnancies of women with type 1 diabetes.

RESEARCH DESIGN AND METHODS One hundred fifteen consecutive women referred at <14 weeks were retrospectively classified as underweight (prepregnancy BMI <18.5 kg/m²; n = 1), normal weight (18.5–24.9; n = 65), overweight (25.0–29.9; n = 39), or obese (≥30.0; n = 10). Gestational weight gain was categorized as excessive, appropriate, or insufficient according to the Institute of Medicine recommendations for each BMI class. Women with nephropathy, preeclampsia, and/or preterm delivery were excluded because of restrictive impact on fetal growth and limited time for total weight gain.

RESULTS HbA_1c was comparable at ∼6.6% (49 mmol/mol) at 8 weeks and ∼6.0% (42 mmol/mol) at 36 weeks between women with excessive (n = 62), appropriate (n = 37), and insufficient (n = 16) gestational weight gain. Diabetes duration was comparable, and median prepregnancy BMI was 25.3 (range 18–41) vs. 23.5 (18–31) vs. 22.7 (20–30) kg/m² (P = 0.05) in the three weight gain groups. Offspring birth weight and birth weight SD score decreased across the groups (3,681 [2,374–4,500] vs. 3,395 [2,910–4,322] vs. 3,295 [2,766–4,340] g [P = 0.02] and 1.08 [−1.90 to 3.25] vs. 0.45 [−0.83 to 3.18] vs. −0.02 [−1.51 to 2.96] [P = 0.009], respectively). In a multiple linear regression analysis, gestational weight gain (kg) was positively associated with offspring birth weight (g) (β = 19; P = 0.02) and birth weight SD score (β = 0.06; P = 0.008) when adjusted for prepregnancy BMI, HbA_1c at 36 weeks, smoking, parity, and ethnicity.

CONCLUSIONS Higher gestational weight gain in women with type 1 diabetes was associated with increasing offspring birth weight independent of glycemic control and prepregnancy BMI.