Risk of congenital heart disease is determined by the age of the mother, not her eggs

As a woman of child-bearing age, I am acutely aware that the longer I postpone having children, the greater the risk that my future offspring may have a medical or developmental disorder. It seems like every few weeks, a new study makes it into the news cycle linking advanced maternal age to disease X or condition Y. (Men don’t get off scotch free – recent studies have linked advanced paternal age to autism.) A study published in Nature this week has shed light on maternal age-associated risk of congenital heart disease and risk-modifying factors.

Despite advances in diagnoses and treatment, congenital heart disease remains one of the leading causes of childhood illness and mortality. Roughly one in 100 children will have minor congenital heart disease whereas one in 1000 will require heart surgery. The risk factors for congenital heart disease include genetics, infections, maternal diabetes and advanced maternal age. A team of researchers led by Dr. Patrick Jay at Washington University School of Medicine asked whether the maternal age effect was based on the age of the mother’s eggs or the mother herself.

To tease apart these scenarios, the researchers carried out reciprocal ovarian transplants where the ovaries of young mice were transplanted into older mice and vice versa. Young mice were less than 100 days old whereas old mice were on average 318 days old (lab mice live on average two and a half years or roughly 850 days). They compared what proportion of the offspring of these two groups of mice had congenital heart disease by looking for ventricular septal defects (VSD). Ventricular septal defects are a common birth defect of the heart where there is a hole in the wall separating the lower chambers of the heart. The offspring of older mothers with young ovaries developed VSD significantly more frequently than the offspring of young mothers with old ovaries. This result provides compelling evidence that the risk of congenital heart disease is associated with the increased age of the mother and not of her eggs. Continue reading