Pregnancy rates and outcomes in women with cystic fibrosis in the UK: comparisons with the general population before and after the introduction of disease-modifying treatment, 2003–17

Objective: To compare pregnancy rates and outcomes for women with cystic fibrosis in the UK with those of the general population and assess the effect of the introduction of disease-modifying treatment. Design: A population-based longitudinal study, 2003–17. Setting: United Kingdom. Population: Women aged 15–44 years in the UK cystic fibrosis (CF) Registry compared with women in England and Wales. Methods: We calculated pregnancy and live-birth rates for the CF population and the general population of England and Wales. For women with CF we compared pregnancy rates before and after ivacaftor was introduced in 2013. We further used CF registry data to assess pregnancy outcomes for mothers with CF, and to assess the relationship between maternal pre-pregnancy lung function and nutritional status and child gestational age. Main outcome measures: Pregnancy and live-birth rates and child gestational age. Results: Of 3831 women with CF, 661 reported 818 pregnancies. Compared with the general population, the pregnancy rate was 3.3 times lower in the CF population (23.5 versus 77.7 per 1000 woman-years); the live-birth rate was 3.5 times lower (17.4 versus 61.4 per 1000 woman-years) with 70% of pregnancies in CF women resulting in live births; termination of pregnancy rates were also lower (9% versus 22%). Pregnancy rates increased post-ivacaftor for eligible women with CF, from 29.7 to 45.7 per 1000 woman-years. There was no association between pre-pregnancy lung function/nutrition status and gestational age. Conclusions: Pregnancy rates in women with CF are about one-third of the rates in the general population with favourable outcomes, and increased for eligible women post-ivacaftor. Tweetable abstract: Pregnancy rates in women with CF are about a third of the rate in England and Wales with 70% live births. Ivacaftor increases the rate.