Prepregnancy weight, maternal weight development from 36 weeks of gestation until delivery, and 1st, 2nd, and 3rd week postpartum, was reported by self-administered questionnaires. Furthermore, the maternal body weight was measured at 4 weeks postpartum (28±9 days) at the department.
Total gestational weight gain was calculated as the difference between self-reported prepregnancy weight and weight just before delivery. Due to possible bias of self-reported prepregnancy weight, these data and inclusion data were collected before randomization, and possible effect of misreporting should thus be of the same size in both groups. Furthermore, to avoid a possible influence of bias, rate of weight gain was calculated as the difference between the measured weight at inclusion and 36 weeks of gestation divided by the number of weeks from inclusion to 36 weeks of gestation.