Abstract
Objectives To examine possible differences in the ability to get pregnant and time to pregnancy (TTP) in women with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA).
Methods Data from RevNatus, a Norwegian nationwide observational register of women with rheumatic diseases planning pregnancy was used. We compared the number of women with SLE and RA achieving pregnancy, TTP and pregnancy outcome (live birth or pregnancy loss). Fifty-three women with SLE and 180 women with RA with a pregnancy wish had follow-up until pregnancy and known pregnancy outcome or at least one year if not achieving pregnancy. With cox regression we adjusted for maternal age, parity and use of disease- modifying antirheumatic drugs (DMARDs).
Results The two groups were similar concerning maternal age, parity, smoking, BMI, educational level, prior pregnancy loss and prior preeclampsia and/or preterm birth. Women with SLE had longer disease duration (p=0.001), more often active disease (p=0.002) and more often used a DMARD (p<0.001). Live birth occurred in 38 (71.7%) women with SLE and 104 (57.5%) women with RA, while pregnancy loss was experienced in 9 (17.0%) and 26 (14.4%), respectively. Six (11.3%) SLE-women and 50 (27.8%) RA-women did not achieve pregnancy during follow-up (Figure 1a). Women with SLE had almost doubled pregnancy rate compared to women with RA (pregnancy ratio 1.91, CI 1.27 to 2.88, p=0.002), and when succeeding they also had a substantially shorter mean TTP (3.9 vs 6.2 months, p=0.017) (Figure 1b). Sixty-five (65/180, 36.1%) RA-women and eight (8/53, 15.1%) SLE-women had a TTP (or censoring) exceeding one year (p=0.006), indicating subfertility.
