Noonan syndrome and pregnancy outcomes

Noonan syndrome is a genetic disorder with high prevalence of congenital heart defects, such as pulmonary stenosis, atrial septal defect and hypertrophic cardiomyopathy. Scarce data exists regarding the safety of pregnancy in patients with Noonan syndrome, particularly in the context of maternal cardiac disease.

We performed a retrospective chart review of patients at Yale-New Haven Hospital from 2012 to 2020 with diagnoses of Noonan syndrome and pregnancy. We analysed medical records for pregnancy details and cardiac health, including echocardiograms to quantify maternal cardiac dysfunction through measurements of pulmonary valve peak gradient, structural heart defects and interventricular septal thickness.

We identified five women with Noonan syndrome (10 pregnancies). Three of five patients had pulmonary valve stenosis at the time of pregnancy, two of which had undergone cardiac procedures. 50% of pregnancies (5/10) resulted in pre-term birth. 80% (8/10) of all deliveries were converted to caesarean section after a trial of labour. One pregnancy resulted in intra-uterine fetal demise while nine pregnancies resulted in the birth of a living infant. 60% (6/10) of livebirths required care in the neonatal intensive care unit. One infant passed away at 5 weeks of age.

The majority of mothers had pre-existing, though mild, heart disease. We found high rates of prematurity, conversion to caesarean section, and elevated level of care. No maternal complications resulted in long-term morbidity. Our study suggests that women with Noonan syndrome and low-risk cardiac lesions can become pregnant and deliver a healthy infant with counselling and risk evaluation.