To investigate the association between the timing of cardiac surgery during pregnancy and both maternal and foetal outcomes.

Studies published up to 6 February 2021 on maternal and/or foetal mortality after cardiac surgery during pregnancy that included individual patient data were identified. Maternal and foetal mortality was analysed per trimester for the total population and stratified for patients who underwent caesarean section (CS) prior to cardiac surgery (Caesarean section (CaeSe) group) vs. patients who did not (Cardiac surgery (CarSu) group). Multivariable logistic regression analysis was performed to evaluate predictors of both maternal and foetal mortality. In total, 179 studies were identified including 386 patients of which 120 underwent CS prior to cardiac surgery. Maternal mortality was 7.3% and did not differ significantly among trimesters of pregnancy (P = 0.292) nor between subgroup CaeSe and CarSu (P = 0.671). Overall foetal mortality was 26.5% and was lowest when cardiac surgery was performed during the third trimester (10.3%, P < 0.01). CS prior to surgery was significantly associated with a reduced risk of foetal mortality in a multivariable model [odds ratio 0.19, 95% confidence interval [0.06–0.56)]. Trimester was not identified as an independent predictor for foetal nor maternal mortality.

Maternal mortality after cardiac surgery during pregnancy is not associated with the trimester of pregnancy. Cardiac surgery is associated with high foetal mortality but is significantly lower in women where CS is performed prior to cardiac surgery. When the foetus is viable, CS prior to cardiac surgery might be safe. When CS is not feasible, trimester stage does not seem to influence foetal mortality.