Objective: To describe the frequency of cardiac complications during pregnancy related to parity in women with congenital heart defects. Methods: A retrospective tertiary single-center study at the Adult Congenital Heart Disease Centre that followed 307 women with congenital heart disease during the years 1997–2015 in Gothenburg, Sweden. Maternal cardiac complications were noted for each pregnancy using medical and obstetric records. The CARPREG I and modified WHO (mWHO) risk classifications were used. Twin pregnancies, miscarriages before gestational week 13, and pregnancy terminations were excluded. Results: Five hundred seventy-one deliveries and 9 late miscarriages were analyzed. The mean parity was 1.74 per woman (range 1–8). Eighty-four (14.6%) maternal cardiac complications were experienced; arrhythmia (5.7%) and heart failure (4.4%) being the most prevalent, and there was 1 maternal death. Heart failure occurred during the first pregnancy in 12 women (3.9%), in the second pregnancy in 8 women (4.3%), and in the third pregnancy in 4 women (7.7%). CARPREG I and mWHO scores were associated with an increased risk of having a cardiac complication, while parity per se was not associated. The OR for having a maternally uneventful second pregnancy if the first pregnancy was without cardiac complications was 5.47 (95% CI 1.76–16.94) after controlling for CARPREG I and mWHO scores. Conclusion: The risk of severe maternal cardiac complications during pregnancy in women with congenital heart disease is low. In this largest analysis to date with a focus on parity in 307 women, the risk classification predicts the maternal outcome more than parity per se. If the first pregnancy is uneventful, the OR is 5.5 for an uneventful second pregnancy if CARPREG I and mWHO scores remain unchanged.