Objective Second pregnancies are usually less complicated than first pregnancies, and have a better outcome in terms of fetal growth. We studied a group of women with heart disease to assess whether their second pregnancy was less complicated and resulted in a larger baby.Design Retrospective case control study.Setting Tertiary referral academic obstetric unit.Population First and second pregnancies in 77 women with congenital and acquired heart disease and in 154 control women were identified.Methods Data were collected from medical and obstetric records.Main outcome measures Cardiac complications, obstetric complications, intra-partum events, birthweight and perinatal complications.Results The rate of obstetric complication was greater in first pregnancies in both the heart disease and the control groups (38% versus 26%, cf. 20% versus 17%). In the heart disease group, the rate of cardiac complications was similar in first and second pregnancies (9% versus 6%). Overall, significantly more perinatal complications were seen in the heart disease group, with no significant difference between first and second pregnancies (36% versus 27%, cf. 14% versus 12%). Median birthweight was significantly higher in second pregnancies in the control group (3308 versus 3519 g P < 0.001), but not significantly different between pregnancies in the heart disease group (3014 versus 3133 g, P = 0.19).Conclusions This case control study demonstrates that women with mild to moderate heart disease have similar pregnancy outcomes in consecutive pregnancies. However, while the median birthweight was higher in the control second pregnancies, it was not increased in the women with heart disease.Keywords Birth, heart disease, obstetric outcomes, parity.Tweetable abstract A study of women with heart disease to assess whether their second pregnancy was less complicated.