Rheumatoid arthritis and outcomes in first and subsequent births based on data from a national birth registry

To examine associations between rheumatoid arthritis (RA) and pregnancy outcomes in first and subsequent births.

Cohort study.

Study based on data registered in the Medical Birth Registry of Norway from the period 1 December 1998 to 31 December 2009.

Singleton births in women recorded with RA (n = 1496) and reference deliveries from the general population (n = 625,642).

Outcomes of first and subsequent births were analyzed separately. First birth was defined as the first delivery of nulliparous women. Associations between RA and maternal and perinatal outcomes were assessed in logistic regression analyses and adjusted for maternal age at delivery, gestational age, smoking habits and for previous cesarean section when relevant.

Maternal and perinatal outcomes.

Vaginal bleeding was observed more often among women with RA both in first pregnancy [adjusted odds ratio (aOR) 1.8, 95% CI 1.3-2.4] and in subsequent pregnancies (aOR 1.4, 95% CI 1.1-1.9). Elective cesarean section was more common among women with RA both in the first birth (aOR 2.0, 95% CI 1.4-2.8) and in subsequent births (aOR 1.5, 95% CI 1.2-2.0). Preterm delivery was more frequent among women with RA than the reference population in first pregnancy (aOR 1.5, 95% CI 1.1-2.0) and in subsequent pregnancies (aOR 1.5, 95% CI 1.1-1.9).

Complications and poor pregnancy outcomes were more often observed in women with RA and the greatest differences were observed in the first pregnancy.