Statistical analysis
REGRESSION, OBESE
Descriptive statistics (frequencies and percentages) were applied to present sociodemographic and obstetrical and baby outcomes per BMI category. Obstetrical and baby outcomes were induction of labor, cesarean section, instrumental delivery, gestational age, Apgar score, birthweight, and admittance to neonatal care unit. Obstetrical outcomes among women classified as obese or severely obese were compared with women of normal weight. We calculated risk ratio and 95 percent confidence intervals using log-binomial regression. Statistically significant differences between the compared groups were defined at the five percent level. As a final step in the analyses, we calculated the stillbirth rate according to gestational week and BMI and included only women who were still pregnant at the time of estimated birth (40 weeks’ gestation). The risk of stillbirth was calculated for women who were still pregnant at the corresponding number of weeks’ gestation, relative to their respective BMI classifications. We used statistical program R (version 3.2.4) and SPSS (version 26).