Maternal obesity is a risk factor for orofacial clefts: a meta-analysis.

Orofacial clefts are the most prevalent birth defects that affect craniofacial structures and implicate genetic and environmental factors in their aetiology. Maternal metabolic state and nutrition have been related to these and other structural malformations, and studies of maternal obesity before pregnancy have shown controversial results about its association with the risk of orofacial clefts in their offspring. Our aim was to assess the combined effect of several single studies of maternal obesity on the risk of orofacial clefts using meta-analysis. We searched for these reports in the PubMed database, and selected 8 studies that met our criteria for eligibility. As a result of this analysis, and using maternal normal weight as a reference, we found that maternal obesity does increase the risk of orofacial clefts in their offspring (OR 1.18, 95% CI 1.11 to 1.26). When these clefts are considered separately, maternal obesity is associated with cleft lip with or without cleft palate (OR 1.13, 95% CI 1.04 to 1.23), and with cleft palate alone (OR 1.22, 95% CI 1.09 to 1.35). Our results support the relation between maternal obesity and orofacial clefts, and confirm two previous meta-analyses that considered fewer studies. However, the molecular mechanisms underlying this statistical evidence have not been fully elucidated.