Maternal Obesity and Infant Heart Defects

Objective : This study determined whether obese women have an increased risk of cardiovascular defects in their offspring compared with average weight women. Research Methods and Procedures : In a case‐control study, prospectively collected information was obtained from Swedish medical health registers. The study included 6801 women who had infants with a cardiovascular defect and, as controls, all delivered women ( N = 812, 457) during the study period (1992 to 2001). Infants with chromosomal anomalies or whose mothers had pre‐existing diabetes were excluded. Obesity was defined as BMI >29 kg/m 2 , and morbid obesity was defined as BMI >35 kg/m 2 . Comparisons were made with average weight women (BMI = 19.8 to 26 kg/m 2 ). Results : In the group of obese mothers, there was an increased risk for cardiovascular defects compared with the average weight mothers [adjusted odds ratio (OR) = 1.18; 95% CI, 1.09 to 1.27], which was slightly more pronounced for the severe types of cardiovascular defects (adjusted OR = 1.23; 95% CI, 1.05 to 1.44). With morbid obesity, the OR for cardiovascular defects was 1.40 (95% CI, 1.22 to 1.64), and for severe cardiovascular defects, the OR was 1.69 (95% CI, 1.27 to 2.26). There was an increased risk for all specific defects studied among the obese women, but only ventricular septal defects and atrial septal defects reached statistical significance. Discussion : In this sample, a positive association was found between maternal obesity in early pregnancy and congenital heart defects in the offspring. A suggested explanation is undetected type 2 diabetes in early pregnancy, but other explanations may exist.