[Does maternal obesity increase the risk of fetal abnormalities? Analysis of 20,248 newborn infants of the Mainz Birth Register for detecting congenital abnormalities].

OBJECTIVE

To investigate the risk of congenital malformations for newborn of obese women (BMI > or = 30) compared with women of average prepregnancy weight.

METHODS

We performed a prospective, population-based case-control study of 20,248 newborn born in the city of Mainz. A total of 1,451 infants (cases) with and 8,088 without congenital malformations (controls) were analysed. The relative risks of associations between obesity and malformations were calculated as odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

The prevalence of malformations in children of obese mothers is 11.1% and thus approximately 4% higher than those of the total study population. There is a significant odds ratio for major malformations (OR 1.3; KI 1.0-1.7). Statistically significant associations were calculated for malformations of the internal urogenital system (OR 1.7; 1.1-2.8), the eyes (OR 5.0; 1.3-20.0) and for orofacial clefts (OR 1.7; 1.1-2.8). Among the specific malformations the highest associations occurred for encephalocele (OR 7.3; 1.1-50.6), common truncus arteriosus (OR 6.3; 1.6-24.8) and Potter sequence (OR 6.3; 1.6-24.8). Adjustment for confounding factors (e.g. maternal diabetes mellitus and age) did not change the odds ratios.

CONCLUSIONS

Our data demonstrate that newborn of obese mothers are at an increased risk for malformations. An adequate prenatal examination of these pregnancies should include ultrasound screening by specially trained ultrasonographers in tertiary units (DEGUM II/DEGUM III) and serum alpha-fetoprotein measurements. Public health campaigns for prevention are advised.