Maternal obesity linked to increased risk of certain congenital heart defects

1. In this large population-based cohort study conducted in Sweden, maternal obesity status was linked to an increased prevalence rate of congenital heart defects with a dose-dependent relationship noted between body-mass index (BMI) and cardiovascular defects.

2. Increased maternal BMI was specifically linked with increased risk of aortic branch defects, atrial septal defects, and persistent ductus arteriosus.

Evidence Rating Level: 1 (Excellent)      

Study Rundown: Maternal obesity is known to cause several pregnancy-related complications. Some prior studies have suggested a connection between maternal obesity and congenial heart defects. This was a population based cohort study in Sweden which assessed the risk of congenital heart defects diagnosed up to five years after birth with maternal body-mass index (BMI) measured at the first antenatal visit. The study found that increased maternal BMI was linked to increased risk of aortic branch defects, atrial septal defects, and persistent ductus arteriosus in a dose-dependent pattern wherein increase in BMI was associated with increased risk.

The strength of this study was the large population-based cohort design, allowing for accurate prevalence estimates. The study also included all congenital cardiac abnormalities diagnosed up to five years of age rather than just those that present at birth, improving the sensitivity of diagnosis. The main limitations of the study was the reliance on BMI to estimate body fat composition which may not be accurate in pregnancy and the lack of data on cardiovascular abnormalities in fetuses that were stillborn or spontaneous abortions.

Click to read the study published in JACC

Click to read an accompanying editorial in JACC

Relevant Reading: The maternal-age-associated risk of congenital heart disease is modifiable

In-Depth [prospective cohort]: This study was a prospective population-based cohort study that included data collected from the Swedish national registries for births between 1992 and 2012. Participants were excluded if they were missing maternal BMI data or had congenital heart disease related to known causes such as genetic disorders or chromosomal abnormalities. Major congenital heart defects were retrieved using registry data and were classified using European Surveillance of Congenital Anomalies (EUROCAT) definitions.

The study found that 1.40% (n=28 628) children had congenital heart defects. Risk of aortic arch defects (p<0.0001), atrial septal defects (p<0.0001), and patent ductus arteriosus (p<0.0001) were found to increase with maternal BMI. Prevalence rate ratio (PRR) was higher with increasing BMI. For ASDs, PRR was 1.08 (95% CI, 1.02 – 1.14) in offspring of overweight mothers and 1.65 (95% CI, 1.34 – 2.03) in offspring of mothers with class 3 obesity. For aortic arch defects, PRR was 1.32 (95% CI, 1.09 – 1.58) in offspring of mothers with class 1 obesity and 1.87 (95% CI, 1.19 – 2.95) in offspring with mothers with class 3 obesity. For PDA, PRR was 1.16 (95% CI, 1.06 – 1.27) in offspring of overweight mothers and 2.32 (95% CI, 1.73 – 3.12) in spring of mothers with class 3 obesity.

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