Associations between inflammatory bowel disease, medication use during pregnancy and overall rates of preterm delivery in the Danish National Birth Cohort, 1996–2003.

HR, hazard ratio; CI, confidence interval.

All estimates were adjusted for parity (0, 1, ≥2), socioeconomic status (6 categories: master’s degree or higher and currently employed, or leader of a business with ≥10 employees; bachelor’s degree and currently employed, or leader of a business with <10 employees; skilled worker (completed vocational training with apprenticeship) and currently employed; unskilled worker or unemployed (short-term); current student; unemployed (long-term)), pre-pregnancy BMI (<20, 20–25, >25), and smoking (non-smoker, smoker) and alcohol consumption (non-drinker, <1 drink/week, ≥1 drink/week) during pregnancy, in strata within the models.

a Delivery before 37 weeks’ gestation.

b The medication use sub-categories do not sum to the total number of women with IBD and CD because 6 women with CD who used AZA were excluded from the medication type-specific analyses.

c Registered pregnancy complications and other potentially relevant conditions in OCS-using women with IBD who delivered prematurely: preterm premature rupture of membrances (five women); severe pre-eclampsia (four women); maternal chronic disease other than IBD (four women, one with spontaneous preterm delivery and three with indicated Caesarian deliveries; the degree to which these conditions, rather than IBD activity, influenced the decision to deliver the fetus early in the medically indicated deliveries, is unclear); breech presentation of fetus (one woman with medically indicated preterm delivery).

Associations between inflammatory bowel disease, medication use during pregnancy and overall rates of preterm delivery in the Danish National Birth Cohort, 1996–2003.