Fertility treatment among women with asthma - A case-control study of 3689 women with live births

Asthma has been linked with prolonged time to pregnancy. Our aim was to explore a possible association between asthma and need for fertility treatment among women with live births.All women enrolled in the Management of Asthma during Pregnancy (MAP) program at Hvidovre Hospital (HH), Denmark, (cases) were each matched with the three consecutive women giving birth at HH (controls). Information from the Danish National Assisted Reproductive Technology registry was cross-linked with the Danish Medical Birth registry to identify live births. The primary outcome of interest was births following fertility treatment.Our sample comprised pregnancies from asthmatic (n=932, cases) and non-asthmatic (n=2757, controls) mothers (n=932), with 12% (n=114) and 8% (n=212), respectively, having had fertility treatment (OR 1.67, 95% CI 1.32-2.13, p<0.001). This association remained statistically significant after adjusting for confounders, incl. BMI (OR 1.31, 95% CI 1.00-1.70, p=0.047). In women ≥35 years, it was 25% (n=63) and 13% (n=82) of cases and controls, respectively, (OR 2.12, 95% CI 1.47-3.07, p<0.001), which also remained statistically significant after adjusting for confounders (OR 1.65, 95% CI (1.11-2.46), p=0.013).A higher proportion of the births from asthmatic mothers, compared to non-asthmatic mothers, involved fertility treatment, not least among women aged 35 years and older.