Women with congenital heart disease who become pregnant face a heightened risk that their infant may be premature or not survive long, according to a report from the Netherlands.

Many women born with heart defects reach childbearing age and wish to become pregnant, the authors explain, but the increased burden imposed on their circulation by pregnancy may have deleterious effects on their health and that of the baby.

Dr. William Drenthen from University Medical Center Groningen and associates reviewed existing studies of complications during pregnancies in women with congenital heart disease. The analysis covered 2491 pregnancies in women with different types of congenital heart disease.

Clinically significant heart failure was the most common complication, affecting almost 5 percent of the pregnancies, the investigators report in the Journal of the American College of Cardiology. Irregular cardiac rhythm and other heart-related events, which are rarely seen in healthy pregnant women, were documented in 11 percent of cases.

“It needs to be said, however, that the given heart failure rate may be an underestimation, considering that early heart failure was an important reason for elective abortion,” the team points out.

Disorders that complicated pregnancy, including high blood pressure and blood clots, were less well documented but rates were higher than normal, the researchers found.

Overall infant mortality was 4 percent, Drenthen and colleagues report, at least partly a result of the relatively high premature birth rate (16 percent) and the recurrence of congenital heart disease, which occurred in up to 8 percent of babies, depending upon the specific defect.

“In the industrialized world, fetal and perinatal mortality is below 1 percent,” the investigators note. “Therefore, the chance of offspring mortality is on average increased by 4 times.”

Nonetheless, they point out, most of the pregnancies were successful.

SOURCE: Journal of the American College of Cardiology, June 19, 2007.