Gestational weight gain and obesity: is 20 pounds too much?

To compare maternal and neonatal outcomes in obese women according to weight change and obesity class.

Cohort study from the Consortium on Safe Labor of 20,950 obese women with a singleton, term live birth from 2002-2008. Risk for adverse outcomes was calculated by multiple logistic regression analysis for weight change categories (weight loss [<0 kg], low [0-4.9 kg], normal [5.0-9.0 kg], high weight gain [>9.0 kg]) in each obesity class (I 30.0-34.9 kg/m(2), II 35.0-39.9 kg/m(2), and III ≥40 kg/m(2)) and by predicted probabilities with weight change as a continuous variable.

Weight loss was associated with decreased cesareans for class I women (nulliparas odds ratio [OR], 0.21; 95% confidence interval [CI], 0.11-0.42; multiparas OR, 0.61; 95% CI, 0.45-0.83) and increased small for gestational age infants (class I OR, 1.8; 95% CI, 1.3-2.5; class II OR, 2.2; 95% CI, 1.5-3.2; class III OR, 1.7; 95% CI, 1.1-2.6). High weight gain was associated with increased large for gestational age infants (class I OR, 2.4; 95% CI, 1.9-2.9; class II OR, 1.7; 95% CI, 1.3-2.1; class III OR, 1.6; 95% CI, 1.3-2.1). As weight change increased, the predicted probability for cesareans and large for gestational age infants increased. The predicted probability of low birthweight never exceeded 4% for all obesity classes, but small for gestational age infants increased with decreased weight change. The lowest average predicted probability of adverse outcomes (cesarean, postpartum hemorrhage, small for gestational age, large for gestational age, neonatal care unit admission) occurred when women (class I, II, III) lost weight.

Optimal maternal and neonatal outcomes appear to occur when weight gain is less than current Institute of Medicine recommendations for obese women. Further study of long-term outcomes is needed with respect to gestational weight changes.