Atlantic DIP: is weight gain less than that recommended by IOM safe in obese women with gestational diabetes mellitus?

Background/objectives: The Institute of Medicine (IOM) recommends gestational weight gain (GWG) of 5-9 kg in women with a body mass index (BMI) ≥ 30 kg/m. Debate continues as to whether GWG less than that recommended is safe in women with gestational diabetes mellitus (GDM). The study objective was to examine maternal and infant outcomes for obese women with GDM who lost weight or gained 0-5 kg during pregnancy.

Subjects/methods: A 7-year retrospective cohort study of pregnancy outcomes for obese women with GDM recorded in the Atlantic Diabetes in Pregnancy database was conducted. We examined pregnancy outcomes for mothers with GDM and a BMI ≥ 30 who either lost weight or gained 0-5 kg (Group 1, n = 237) and women who gained 5-9 kg (Group 2, n = 77). We further divided groups 1 and 2 into women treated by diet only (GDM-D) (n = 120) and those requiring additional treatment with insulin (GDM-I) (n = 194).

Results: GDM-D women in Group 1 were more likely to deliver earlier (38.9 vs 39.8 weeks, p < 0.01), to develop pregnancy induced hypertension (PIH) (15.4% v 0%; p = 0.02) or have a post-partum haemorrhage (PPH) (13.2% vs 0, p = 0.03) compared to women in Group 2. Rates of prematurity were higher in group 1 vs 2 (14.3% vs 0%, p = 0.03). However, further logistic regression analysis adjusted for smoking status, family history of diabetes, ethnicity and age determined no significant difference in maternal or infant outcomes for women in Group 1 compared to those in Group 2.

Conclusion: In our population, weight gain less than IOM guideline appears safe and is not associated with any further increase in adverse outcomes. However, validation through a prospective study with a larger obese GDM cohort is required before the findings presented here could be recommended for routine clinical use.