Birthweight and pregnancy outcomes in obese class II women with low weight gain: A retrospective study

INTRODUCTION: To determine if weight gain below the institute of medicine (IOM) guidelines improves pregnancy outcomes and influences birthweight for women with class II obesity. MATERIALS AND METHODS: We retrospectively included 996 women with class II obesity with singleton gestations and delivered at term in two hospitals providing level III maternal care between January 2006 and December 2015. Women were classified into three groups: weight gain within IOM recommendations (≥5-≤9kg), low weight gain (≥0-<5kg), and weight loss (<0kg). Maternal complications and birth weight were reported in all groups. The group presenting weight gain within IOM recommendations was considered as the reference group. RESULTS: 424 women (42.5%) constituted the reference group and presented weight gain within IOM recommendations; whereas 370 (37.1%) presented low weight gain and 202 (20.3%) presented weight loss. The rate of birthweight above 4000 g was reduced in women with low weight gain (odds ratio (OR) = 0.62 [0.42–0.93]; p = 0.02) and in women with weight loss (OR = 0.58 [0.35–0.96]; p = 0.02). However, the rates of small for gestational age fetuses (SGA) < 10(th) percentile was increased in women with weight loss (OR = 1.63 [1.03–2.58]; p = 0.02). Maternal and neonatal complications were not significantly different between groups. CONCLUSION: While low weight gain in women with class II obesity may reduce macrosomia without excessive risk of SGA, it has no effect on maternal and neonatal complication rates.