Pregnancy weight gain charts for obese and overweight women.

OBJECTIVE: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: These charts are an innovative tool for studying the association between gestational weight gain and adverse pregnancy outcomes.