Within-Population Average Ranges Compared With Institute of Medicine Recommendations for Gestational Weight Gain

OBJECTIVE: To compare the risk for pregnancy outcomes by gestational weight gain with the Institute of Medicine criteria and empirically established average ranges of gestational weight gain. METHODS: In a population-based data set comprising 678,560 singleton deliveries in Bavarian obstetric units from 2000 to 2007, we calculated the prevalence of adverse short-term pregnancy outcomes within the gestational weight-gain ranges recommended by the Institute of Medicine. We then compared these for gestational weight gain within data-based interquartile ranges (25th to 75th percentile) and interdecile ranges (10th to 90th percentile) of gestational weight gain by maternal weight category (underweight, normal weight, overweight, and obese). RESULTS: In underweight and normal-weight mothers, adherence to Institute of Medicine criteria was significantly associated with fewer preterm deliveries and small-for-gestational-age births (prevalence [95% confidence interval] for preterm delivery in normal-weight women: 5.33 [5.23-5.43] within Institute of Medicine criteria compared with 5.45 [5.36-5.54] in interquartile range). Overweight and obese mothers gaining weight within the Institute of Medicine recommendations had less preeclampsia and nonelective caesarean deliveries but had higher risks for gestational diabetes, small-for-gestational-age births, preterm delivery, and perinatal mortality compared with gestational weight gain within the respective interquartile ranges and interdecile ranges (prevalence for preterm delivery in overweight women: 8.14% [7.87-8.42] within Institute of Medicine criteria compared with 5.77% [5.60-5.93] in interquartile range). CONCLUSION: Although underweight and normal-weight women should be encouraged to aim for a gestational weight gain according to Institute of Medicine guidelines, different gestational weight gain recommendations in overweight and obese women might lessen some adverse short-term pregnancy outcomes. (Obstet Gynecol 2010;116:1111-8)