Risk of Pregnancy Complications in Relation to Maternal Prepregnancy Body Mass Index: Population-Based Study from Finland 2006-10.

BACKGROUND: Overweight and obesity are well-known risk factors for several pregnancy-related complications, but the nature of the association between maternal adiposity and these complications has been less studied. The objective of the present study was to examine the shape and the magnitude of the association between maternal prepregnancy body mass index and the risk of gestational diabetes, pre-eclampsia of different severity, gestational hypertension, and obstetric cholestasis among Finnish primiparae women.

METHODS: Data on all primiparae women who delivered a singleton newborn in Finland between 2006 and 2010 were identified from the Finnish Medical Birth Register and the Finnish Hospital Discharge Register (n = 119 485). Associations were analysed using restricted cubic spline regression and logistic regression models.

RESULTS: There was a nonlinear dose-dependent association between body mass index and the risk of gestational diabetes, pre-eclampsia, and gestational hypertension, and the risk was increased already among normal weight primiparae women. However, in the presence of pre-existing hypertension or diabetes body mass index was not associated with the risk of pre-eclampsia.

CONCLUSIONS: Efforts to reduce prepregnancy overweight and obesity need to be intensified, and also, measures to better identify those normal weight women who are at increased risk of gestational diabetes, pre-eclampsia and gestational hypertension should be developed.