IntroductionThere are an increasing number of reports of pregnancy in transplant recipients but many questions remain regarding the effect of the transplant on pregnancy outcome, the pregnancy on the graft and the medication on the fetus. The majority of studies reporting outcomes in transplant recipients have focused on women with kidney transplants, and have included retrospective, voluntary registries or single centre studies.MethodsThe UK Obstetric Surveillance System (UKOSS) was used to prospectively identify all pregnant women with a liver or cardiothoracic transplant in the United Kingdom, between January 2007 and January 2012. Data were collected on demographics, transplant characteristics, immunosuppression regimens, antenatal care, maternal, graft and neonatal outcomes. In an exploratory analysis, we tested for associations between “poor fetal outcome” and medications used before or during pregnancy.Results and conclusionsWe report 62 pregnancies in 56 liver transplant recipients and 14 pregnancies in 14 cardiothoracic transplant recipients (including 10 heart, three lung and one heart-lung recipient). Liver transplant recipients, in comparison to cardiothoracic, had similar livebirth rates (92% vs. 87%) but better fetal outcomes (median gestational age 38 weeks vs. 35 weeks; median birthweight 2698 g vs. 2365 g), fewer caesarean deliveries (47% vs. 62%), fewer maternal intensive care (ICU) admissions (19% vs. 29%) and fewer neonatal ICU admissions (25% vs. 54%). Nine women (12%) were taking mycophenolate mofetil at conception, which was associated with adverse fetal outcomes. Pregnancy in transplant recipients may have successful outcomes, but complication rates are high, emphasising the role of pre-conception counselling and further research into the long-term effect on maternal and graft survival rates.