Pregnancy outcomes in the super obese, stratified by weight gain above and below institute of medicine guidelines

OBJECTIVE: To examine the association of antenatal weight gain above and below the 2009 Institute of Medicine (IOM) guidelines in the super-obese population (body mass index [BMI] of 50 or higher) on the maternal and neonatal morbidities of gestational hypertension or preeclampsia (pregnancy-induced hypertension), gestational diabetes mellitus, cesarean delivery, birth weight more than 4,000 g and more than 4,500 g, low birth weight, and preterm birth.

METHODS: The effect of gestational weight gain was assessed in this retrospective cohort study using California birth certificate and patient discharge diagnosis data. Unconditional logistic regression was used to calculate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) as a function of antenatal weight gain. Weight gain within 2009 IOM guidelines (11-20 pounds) served as the reference group.

RESULTS: The study population consisted of 1,034 women. Women gaining below, within, and above IOM guidelines accounted for 38.3, 23.5, and 38.2%, respectively. Weight gain below IOM guidelines was not associated with a statistically increased odds of preterm birth (OR 1.82, 95% CI 0.60-5.59) or low birth weight (OR 1.20, 95% CI 0.57-2.49); however, birth weight more than 4,000 g was significantly reduced (OR 0.50, 95% CI 0.32-0.77). Excessive weight gain statistically increased the odds of pregnancy-induced hypertension (OR 1.96, 95% CI 1.26- 3.03) and cesarean delivery (OR 1.40, 95% CI 1.00-1.97) while not appearing to protect against the delivery of low-birth-weight neonates (OR 0.84, 95% CI 0.40-1.78).

CONCLUSION: Weight gain below the current guidelines in the super-obese cohort is not associated with an increase in maternal or neonatal risk while decreasing the odds of delivering a macrosomic neonate. Women with BMIs of 50 or higher may warrant separate gestational weight gain recommendations.