Maternal and paternal body mass index and offspring obesity: a systematic review.

BACKGROUND/AIMS It has been hypothesized that the intrauterine environment is an independent factor in obesity development. If so, the maternal effect is likely to be a stronger influencing factor ('fetal overnutrition hypothesis'). We aimed to systematically evaluate the associations of offspring body mass index (BMI, or adiposity) with pre-pregnancy BMI (or adiposity) of the mother and the father. METHODS The Medline, Embase and Cochrane Library databases were searched in March 2012. RESULTS Seven cohort studies were eligible for the analysis. Among these, 2 groups of trials presented different data from the same parent-offspring cohorts (the Avon Longitudinal Study of Parents and Children, ALSPAC, and the Mater-University Study of Pregnancy, MUSP). In total, 3 large birth cohorts and 1 additional small study were identified. Three studies provided a direct comparison of parent-offspring associations, with a statistically stronger maternal influence found only in the MUSP cohort. Equivocal results were obtained from all studies describing the ALSPAC cohort. The parental effect (indirectly estimated based on the presented odds ratio) was similar in the Finnish cohort. In 1 additional small study, maternal BMI was found to be a strong predictor of childhood obesity. CONCLUSIONS There is only limited evidence to support the 'fetal overnutrition hypothesis'.