Pregnancy weight gain charts for obese and overweight women

Reference charts for classifying and monitoring pregnancy weight gain in severely obese women do not exist. The goal was to construct pregnancy weight-gain-for-gestational-age z-score charts for overweight and obese mothers, stratified by severity of obesity.

Serial weight gain measurements were abstracted from 1047, 1202, 1267, and 730 overweight, class I, II, and III obese women, respectively, delivering uncomplicated term pregnancies at Magee-Womens Hospital in Pittsburgh, PA. Multi-level linear regression models were used to express serial weight gain measurements as a function of gestational age.

There were a median [interquartile range] of 11 [9-12] and 11 [9-13] serial weight measurements for overweight and obese (class I, II, and III) women, respectively. The rate of weight gain was minimal until 15-20 weeks and then increased in a slow, linear manner until term. The slope of weight gain flattened as pre-pregnancy BMI increased. Charts were created describing the mean, standard deviation, and select percentiles of weight gain in class I, II, and III obese and overweight pregnancies.

These charts are an innovative tool for studying the association between gestational weight gain and adverse pregnancy outcomes.