Background — Pregnant women with heart disease (HD) are at increased risk for cardiac (CV) complications. However, the frequency of neonatal (NE) complications in pregnant women with HD relative to pregnant women without HD has not been examined. Methods and Results — Pregnant women with HD were prospectively monitored during 302 pregnancies. The frequency of NE and CV complications was compared with those in a control group without HD during 572 pregnancies. The frequency of NE complications was higher in the HD group (18% versus 7%; HD versus controls). The NE complication rate was lowest in pregnancies of women age 20 to 35 years who did not smoke during pregnancy, did not receive anticoagulants, and had no obstetric risk factors: 4% in control patients, 5% in HD patients with no cardiac risk factors for NE complications (left heart obstruction, poor functional class, or cyanosis), and 7% in HD patients with ≥1 such risk factor. In contrast, the event rate in pregnancies of controls age <20 or >35 years who had obstetric risk factors or multiple gestation or who smoked was 11%. In the HD group, women age <20 or >35 years who had obstetric risk factors or multiple gestation, who smoked, or who received anticoagulants experienced an even higher NE complication rate (27% with no cardiac risks for NE events and 33% in the presence of ≥1 cardiac risk factors). The frequency of CV complications was higher in the HD group (17% versus 0%; HD versus controls). Conclusion — Pregnant women with HD are at increased risk for both NE and CV complications. The risk for NE adverse events in pregnant women with HD is highest in those with both obstetric and cardiac risk factors for NE complications.