The impact of pregnancy on mortality and lung function in cystic fibrosis patients.

Background: As the lifespan of people with cystic fibrosis (pwCF) improves, more individuals are pursuing pregnancy. Historically, pregnancy was not recommended in this population; however, more recent evidence has revealed inconsistent survival and lung function outcomes. Our aim was to assess the differences in survival and lung function between pregnant and never-pregnant pwCF and to provide updated recommendations for contemporary clinical practice.

Methods: In this retrospective matched parallel cohort study, data was collected from the American Cystic Fibrosis Foundation Patient Registry (CFFPR) from 1999 to 2019. 1743 adult pwCF with a reported pregnancy were matched with 1743 never-pregnant patients. Regression models were developed to estimate associations between patient characteristics, pregnancy, and outcomes. The primary endpoint was the probability of survival comparing pregnant and never-pregnant pwCF, while the secondary endpoint was lung function over time.

Results: The study cohort (n = 3486) had a mean age of 24.96 years. There was no significant difference in survival probabilities between pregnant and never-pregnant pwCF (56.2 %, CI^{95 %}: 51.3 %-61.5 % vs. 55.8 %, CI^{95 %}: 52.1 %-59.7 %, p = 0.5). The multivariable time-dependent Cox regression analysis resulted in a significantly lower mortality hazard rate for pregnant cohorts (HR:0.78, p < 0.01). There was no significant association between pregnancy and lung function over time (0.99, p = 0.21).

Conclusion: Pregnancy was associated with a reduced hazard of death compared to never-pregnant pwCF and did not demonstrate a significant impact on lung function. Therefore, pregnancy should not be generally discouraged in pwCF and clinicians should evaluate pregnancy risks and benefits on an individualized basis.