Longitudinal Study of Maternal BMI in Successive Pregnancies

Objective: This longitudinal observational study examined BMI changes between successive pregnancies. Methods: The computerized medical records of women who attended a large maternity hospital between 2009 and 2017 for their first and second singleton deliveries were analyzed. Women who had their weight first measured after 15 weeks of gestation in either pregnancy were excluded. Results: Of the 9,724 women, the incidence of obesity increased from 11.6% in the first pregnancy to 16.0% in the second. The mean interpregnancy interval was 32.5 ± 15.7 months, and median BMI change was +0.6 kg/m2 (interquartile range 2.2; P < 0.001). Overall, 10.3% (1,006/9,724) developed overweight and 5.9% (571/9,724) developed obesity by the second pregnancy. Of the nulliparas in the overweight category, 20.6% (526/2,558) entered the obesity category. The development of obesity by the second pregnancy was independently associated with a longer interpregnancy interval, formula feeding at hospital discharge, taking antidepressants or anxiolytics, and postnatal depression. Professional/managerial employment was associated with a lower odds ratio of developing obesity. Conclusions: Maternal obesity increased between the first and second pregnancy, with one-fifth of nulliparas in the overweight category developing obesity. Pregnancy-related factors were identified as predictors of developing obesity. Further research is needed to assess whether interventions targeting these related factors could optimize maternal weight management between pregnancies.