Morbidity in pregnant women with a prosthetic heart valve

Background — Women with a prosthetic heart valve are perceived to be at higher risk for adverse outcomes, but their absolute and relative risk of experiencing maternal morbidity and cardiac complications is largely unknown.

Objective — To determine the risk of maternal morbidity and cardiac complications in women with prior heart valve replacement, compared to matched counterparts without known cardiac disease.

Study Design — A retrospective population-based matched cohort study was completed in the province of Ontario, Canada, where there is universal healthcare. Included were all women of child-bearing age who had bioprosthetic or mechanical replacement of the mitral or aortic valve, April 1994 to March 2016 (valve replacement group). Those in the valve replacement group, and who had at least one birth, were 1:4 matched to a community comparison group without heart disease, and who also had at least one birth. Matching was by maternal age at cohort entry, year of cohort entry, geographic area, income level and age at first birth. Maternal outcomes included severe maternal morbidity; all-cause mortality; cardiac morbidity; as well as a prolonged hospital length of stay > 7 days. Relative risks and 95% confidence intervals were further adjusted for age at birth and immigration status.

Results — There were 90 livebirths among the 64 women in the valve replacement group, and 404 livebirths among the 253 women in the matched community comparison group. There were no stillbirths. Severe maternal morbidity occurred in 13 pregnancies (14.4%) in the valve replacement group, and 6 (1.5%) in the community comparison group (adjusted relative risk 9.73, 95% confidence interval 3.70 to 25.59); there were no maternal deaths. The corresponding rates of prolonged hospital length of stay were 37.8% and 18.8% (adjusted relative risk 2.33, 95% confidence interval 1.48 to 3.67).

Conclusion — Pregnant women who had aortic or mitral valve replacement were more likely to experience severe maternal morbidity, as well as prolonged hospital length of stay, than matched counterparts without heart disease. This information can enhance shared decision making about the timing of valve replacement and pregnancy planning in young and middle aged women.