Body mass index and gestational weight gain as factors predicting complications and pregnancy outcome

PURPOSE: To evaluate the impact of body mass index (BMI) at the beginning of pregnancy and weight gain on pregnancy outcome so that this measure can be implemented and valued by prenatal care health services. METHOD: Cross-sectional population-based study of all births in the only two hospitals in Rio Grande city (Brazil), in 2007. Among the 2,557 mothers interviewed, it was possible to calculate BMI in only 1,117. The Stata 11 software was used for data analysis. Logist regression was applied to the outomes involving diabetes mellitus, premature labor and cesarean section. Regarding birth weight, data were adjusted by multinomial logistic regression using as base category the group of 2,500 to 4,000 g. The level of significance was set at p-value <0.05 in a two-tailed test. RESULTS: There was no increased risk of hypertension or diabetes in patients in the different groups of BMI and weight gain. The risk of preterm delivery was evident in the group with a weight gain <= 8 kg (p<0.05). Regarding the route of delivery, it was observed that the higher the BMI in early pregnancy (p=0.001) and the greater the weight gain during pregnancy (p=0.004), the greater the risk of surgical delivery, which reached 11% in the group of obese mothers (p=0.004) and 12% in the group with a weight gain >= 17 kg (p=0.001). The weight of the newborns was influenced by BMI and weight gain, and the higher the BMI in early pregnancy and the gestational weight gain, the greater the risk of macrosomia. CONCLUSION: The monitoring of BMI and weight gain during pregnancy is a low cost and useful procedure for the establishment of nutritional interventions aimed at reducing maternal and fetal risks.