Baseline Cystic fibrosis disease severity has an adverse impact on pregnancy and infant outcomes, but does not impact disease progression

•Pregnancies have only a mild impact on disease progression in CF severe patients.•CF disease severity has an adverse impact on women's fertility.•PI increases the risk for delivering an SGA newborn.•Pregnancies in severe CF patients can have a good prognosis. With increasing longevity and quality of life in adults with Cystic fibrosis (CF), growing maternity rates are reported. Women with severe CF are becoming pregnant, with unpredictable maternal and fetal outcomes. To determine how baseline disease severity, pancreatic insufficiency (PI) and Pseudomonas aeruginosa (PA) infection affect fertility, the pregnancy course, delivery, neonatal outcome, and subsequent disease progression. A multicenter-retrospective cohort study. Data on patients that had been pregnant between 1986-2018 was collected from ten CF centers worldwide. Disease severity [mild or moderate-severe (mod-sev)] was defined according to forced expiratory volume % predicted in 1 second (FEV1) and body mass index (BMI). Three time periods were compared, 12 months prior to conception, the pregnancy itself and the 12 months thereafter. Data was available on 171 pregnancies in 128 patients aged 18-45 years; 55.1% with mod-sev disease, 43.1% with PI and 40.3% with PA. Women with mod-sev disease had more CF-related complications during and after pregnancy and delivered more preterm newborns. However, FEV1 and BMI decline were no different between the mild and mod-sev groups. A more rapid decline in FEV1 was observed during pregnancy in PI and PA infected patients, though stabilizing thereafter. PI was associated with increased risk for small for gestational age infants. Baseline disease severity, PA infection and PI have an adverse impact on infant outcomes, but do not impact significantly on disease progression during and after pregnancy. Consequently, pregnancies in severe CF patients can have a good prognosis.