Pregnancy in women with congenital heart defects: what are the risks?

Maternal and fetal risk The pregnancy related changes in intravascular volume, cardiac output, and systemic vascular resistance may result in maternal or fetal deterioration in women with CHD. Pregnancy in women with CHD, not complicated by Eisenmenger syndrome, is associated with low mortality. However, they continue to be at risk for other cardiac complications such as arrhythmia, heart failure, or stroke. Poor maternal functional class, cyanosis, and the presence of significant aortic stenosis have been repeatedly mentioned as potential risk factors for maternal cardiac deterioration. Maternal cyanosis is also a risk factor for fetal and neonatal complications. 5 One recent study reported a 12% likelihood of a livebirth when the arterial oxygen saturation at rest was < 85%; the livebirth rate improved to 63% when the oxygen saturation was > 85%. In a recent study of 252 pregnancies in women with heart disease, the following independent predictors of cardiac events were identified: + poor maternal functional class or cyanosis + history of transient ischaemic attack or heart failure + history of arrhythmia + left heart obstruction + myocardial dysfunction. These five predictors can be combined into a risk score to predict the likelihood of maternal cardiac complications. This risk score is presently being evaluated in a prospective national study being completed in Canada. Although the very good pregnancy outcomes reported by Genoni and colleagues will be encouraging to patients who had Mustard repair as well as to their physicians, in view of the limited data available, 7–11 prospective studies will provide a better estimate of maternal and fetal risk. As the number of pregnant women with each complex congenital malformation are limited, prospective cohort studies examining this patient population will need to adopt a multicentre design with similar study organisation as randomised clinical trials. The prospective determination of pregnancy outcomes in women with CHD will enhance not only their preconception counselling but also their clinical care during pregnancy.