Maternal Overweight and Baby’s Heart Defects
Adapted from Maternal Overweight and Obesity and Risk of Congenital Heart Defects published in January 2019 issue of the Journal of the American College of Cardiology.
In the past, increased maternal weight was shown to lower the probability of a successful outcome of fertility treatments.
A new study by Swedish researchers found that increased maternal body-mass index (BMI) was associated with increased risk of congenital heart defects in offspring.
Increasing maternal BMI was specifically linked with increased risk of aortic branch defects, atrial septal defects, and persistent ductus arteriosus.
A total of 2,050,491 live singleton infants born between 1992 and 2012 were included in this study.
Prenatal maternal body mass index (BMI) was categorized as underweight (BMI less than 18.5), normal weight (BMI 18.5 to less than 25), overweight (BMI 25 to less than 30), obesity class I (BMI 30 to less than 35), class II (BMI 35 to less than 40), and class III (BMI 40 and above).
Congenital heart defect rates in offspring increased as maternal BMI increased. Rates of atrial septal defects and patent ductus arteriosus in term infants were higher among offspring of mothers with increased BMI. Rates of aortic arch defects and transposition of the great arteries were doubled in offspring of mothers with severe obesity.
The mechanism by which obesity increases the risk of fetal malformations may be related to diabetes, insulin resistance, inflammation, endothelial dysfunction, and oxidative stress causing adverse gene expression and organ development.
Prior animal studies have shown that hyperglycemia is associated with increased risks of congenital malformations, and that supplementation with antioxidants (vitamins C and E) could potentially inhibit damage by free oxygen radicals.
Most remarkably, exercise, whether begun by mothers at a young age or later in life, can mitigate the risk. Thus an intervention aimed at the mother can meaningfully reduce offspring’s risk of congenital heart disease.