Impact of pre-gravid body mass index and body mass index change on preeclampsia and gestational diabetes in singleton and twin pregnancies

Objective: To examine pre-gravid body mass index (BMI) and gestational BMI change impact on preeclampsia and gestational diabetes mellitus (GDM). Methods: Retrospective population-based cohort study. Data from Slovenian National Perinatal Information System were analyzed for the period 2002-2011. Three singleton controls were matched by parity and maternal age to each twin pregnancy delivered at >36 weeks. Student's t test was used to compare pre-gravid BMI and gestational BMI change in different groups (p<0.05 significant). Results: 2046 twin and 6138 singleton pregnancies were included. Twin and singleton patients with preeclampsia or GDM had higher pre-gravid BMI (p<0.001). Gestational BMI change was smaller in twins with GDM (p<0.001), and not associated with preeclampsia (p = 0.07). Smaller gestational BMI change in singleton pregnancies was associated with GDM (p<.001), and greater BMI change with preeclampsia (p = 0.004). Conclusions: Pre-gravid BMI is more strongly associated with preeclampsia and GDM in twin and singleton pregnancies than gestational BMI change. Smaller gestational BMI change in GDM pregnancies reflect the importance of dietary counseling.