Risk for Congenital Heart Defects in Offspring of Mothers With Obesity

Although congenital heart defects are more frequent in offspring of mothers with overweight or obesity, the relationship between maternal overweight and obesity and risk for complex and specific heart defects is not well defined.

The risk for offspring aortic branch defects, atrial septic defects, and persistent ductus arteriosus increases with maternal obesity severity, according to a study published in the Journal of the American College of Cardiology,

To assess the association between maternal overweight and obesity and rate of complex and specific heart defects in their offspring, researchers followed a cohort of 1,747,412 children for ≤5 years after birth. They used national registries to retrieve data on maternal and infant characteristics and diagnoses of congenital heart defects. Included mothers did not have pregestational diabetes and were categorized according to body mass index (BMI) as underweight, normal weight, overweight, or obesity class I, II, or III.

Congenital heart defect rates in offspring increased as maternal BMI increased. Defects were also slightly more common in girls, in first offspring, and in offspring whose mothers were short (<155 cm) or ≥35 years old; 1.4% of included infants (n=28,628) were diagnosed during the study period with ≥1 congenital heart defect; 3321 of these had complex heart defects.

Compared with offspring of normal-weight mothers, offspring of mothers who were classified as class III obese were approximately twice as likely to have transposition of the great arteries (prevalence rate ratio: 1 vs 1.85, respectively) or aortic arch defects (1 vs 1.87, respectively). Likewise, persistent ductus arteriosus became significantly more likely as obesity severity increased. There were, however, no significant associations between maternal obesity and tetralogy of Fallot, atrioventricular septal defects, or single-ventricle heart.

Limitations to this study included lack of information about malformations in stillbirths, miscarriage, and induced abortions.

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“The most vulnerable period of fetal organ development occurs in the first 8 weeks of pregnancy,” the researchers said, adding, “primary prevention aiming at reducing the prevalence of overweight and obesity in women in reproductive age is essential for reducing obesity-related risks of congenital heart defects.”

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Persson M, Razaz N, Edstedt Bonamy A-K, Villamor E, Cnattingius S. Maternal overweight and obesity and risk of congenital heart defects. J Am Coll Cardiol. 2019;73(1):44-53.