Prosthetic heart valves in pregnancy, outcomes for women and their babies: a systematic review and meta-analysis.

Background: Historically, pregnancies among women with prosthetic heart valves have been associated with an increased incidence of adverse outcomes.
Objectives: Systematic review to assess risk of adverse pregnancy outcomes among women with a prosthetic heart valve(s) over the last 20 years.
Search Strategy: Electronic literature search of Medline, The Cochrane Library, Cumulative Index to Nursing and Allied Health Literature and Embase to find recent studies.
Selection Criteria: Studies of pregnant women with heart valve prostheses including trials, cohort studies and unselected case series.
Data Collection and Analysis: Primary analysis calculated absolute risks and 95% confidence intervals (CI) for pregnancy outcomes using a random effects model. The Freeman-Tukey transformation was utilised in secondary analysis due to the large number of individual study outcomes with zero events.
Main Results: Eleven studies capturing 499 pregnancies among women with heart valve prostheses, including 256 mechanical and 59 bioprosthetic, were eligible for inclusion. Pooled estimate of maternal mortality was 1.2/100 pregnancies (95% CI 0.5-2.2), for mechanical valves subgroup 1.8/100 (95% CI 0.5-3.7) and bioprosthetic subgroup 0.7/100 (95% CI 0.1-4.5), overall pregnancy loss 20.8/100 pregnancies (95% CI 9.5-35.1), perinatal mortality 5.0/100 births (95%CI 1.8-9.8) and thromboembolism 9.3/100 pregnancies (95% CI 4.0-16.5).
Conclusions: Women with heart valve prostheses experienced higher rates of adverse outcomes than expected in a general obstetric population; however, lower than previously reported. Women with bioprostheses had significantly fewer thromboembolic events compared to women with mechanical valves. Women should be counselled pre-pregnancy about risk of maternal death and pregnancy loss. Vigilant surveillance by a multidisciplinary team throughout the perinatal period remains warranted for these women and their infants.
Tweetable Abstract: Metaanalysis suggests improvement in #pregnancy outcomes among women with #heartvalveprostheses.
(© 2015 Royal College of Obstetricians and Gynaecologists.)