To compare fertility rates in women with RA, other chronic arthritides (OCAs) and JIA with reference women from the general population.
Each woman from a Norwegian patient registry was matched by year of birth with 100 reference women randomly selected from the National Population Registry. Data linkage of patients and references with the Medical Birth Registry of Norway (MBRN) identified all offspring in patients and references until October 2007, and indirectly also nulliparous (childless) women. Groups were compared with Mann-Whitney U-test for continuous variables and chi-squared tests for categorical variables. Poisson regression analysis was applied to calculate relative fertility rates in the diagnostic groups vs references.
Among 631 patients 849 children were registered in MBRN. Of these, 289 children (34.0%) were born after time of diagnosis vs 44.3% in references. Altogether, 206 of 631 patients (32.6%) were nulliparous vs 26.4% in references (P < 0.001). Among RA patients, 28.4% (96 of 338) were nulliparous vs 24.5% in references (P = 0.09), 30.7% (67 of 218) in OCA patients vs 24.5% in references (P = 0.03) and 57.3% (43 of 75) in JIA patients vs 40.9% in references (P = 0.004). Adjusted relative fertility rates in RA, OCA and JIA after diagnosis were 0.88, 0.84 and 0.84, respectively, compared with references.
A higher proportion of women with chronic inflammatory arthritides were nulliparous compared with references, and relative fertility rates were reduced in all patient groups.