Weight loss in obese pregnant women and risk for adverse perinatal outcomes

To examine the association between weight loss in obese pregnant women and relevant maternal and neonatal outcomes.

All liveborn singleton term (37 weeks of gestation or greater) births in obese women between 2009 and 2011 in Flanders (the northern part of Belgium) were included (N=18,053). Outcomes assessed included gestational hypertension, low (2,500 g or less) birth weight, small-for-gestational-age (less than the 10th percentile) neonates, macrosomia (birth weight 4,000 g or greater), large-for-gestational-age (greater than 90th percentile) neonates, emergency caesarean delivery, and admission to a neonatal intensive care unit. Risk for adverse outcomes was calculated by multiple logistic regression analysis for weight change categories (greater weight loss [5 kg or greater], lesser weight loss [between 0 and 5 kg], low gestational weight gain [0 or greater and less than 5 kg], adequate gestational weight gain [5 or greater to 9 kg or less, reference], and excessive gestational weight gain [greater than 9 kg]) in each obesity class (I 30-34.9, II 35-39.9, III 40 or greater) adjusted for parity and maternal and gestational age.

In the total population, 854 (4.7%) obese pregnant women reported weight loss. Weight loss and low weight gain were associated with a decreased incidence of gestational hypertension for women with class I obesity (greater weight loss adjusted odds ratio [OR] 0.31, 95% confidence interval [CI] 0.11-0.84; lesser weight loss adjusted OR 0.46 95% CI 0.21-0.99; low gain adjusted OR 0.71 95% CI 0.54-0.93), a reduction in the rate of emergency cesarean delivery, but only in those with class II obesity (greater weight loss adjusted OR 0.24, 95% CI 0.07-0.78; lesser weight loss adjusted OR 0.50, 95% CI 0.26-0.97; low gain adjusted OR 0.55, 95% CI 0.38-0.79), and decreased macrosomia and large-for-gestational-age neonates in women in all classes of obesity, with the highest decrease for women with class III obesity (greater weight loss adjusted OR 0.15, 95% CI 0.05-0.49; lesser weight loss adjusted OR 0.37, 95% CI 0.15-0.90 for macrosomia). No association between weight loss and low birth weight, small-for-gestational-age neonates, or admission to the neonatal intensive care unit was shown in the different obesity classes.

Weight loss in obese pregnant women was associated with reduced perinatal risks but not with the rate of low birth weight or small-for-gestational-age neonates in obese women from class III in this affluent region. Stratification of recommended gestational weight gain ranges in obese women should be considered.

II.