To study the association between miscarriage in rheumatoid arthritis (RA) patients and serologic findings, disease activity, and antirheumatic drug treatment, and to study disease activity and reproductive outcomes after a miscarriage.
Within a nationwide prospective cohort study (Pregnancy-Induced Amelioration of RA study), patients with RA were followed up from preconception until 6 months after delivery or miscarriage. Univariate and logistic regression analyses were performed to assess variables of interest, with covariates included in the models if the P value for association with miscarriage was <0.20 and subsequently excluded if the P value was >0.10.
Among 162 pregnancies, 28 miscarriages occurred (17.3%; 95% confidence interval 12.2-24.0%). Women who miscarried were older than women with an ongoing pregnancy. Women who miscarried tended to be more often positive for anti-citrullinated protein antibodies (ACPAs), to have higher disease activity scores, and to have more often received methotrexate (MTX) therapy in the past. Logistic regression showed a tendency toward a higher likelihood of miscarriage in association with increasing age (P = 0.065) and presence of ACPAs (P = 0.092). After miscarriage, 33% of women had a flare of RA. Within 1 year, 68% of women became pregnant again, 14% stopped trying to conceive, and 11% were lost to followup. The live birth rate of the subsequent pregnancy was 90%.
The miscarriage rate in the PARA cohort is comparable to that in the general population. Due to the low frequency of miscarriages in this study, the associations between miscarriage in RA and the presence of ACPAs, disease activity, and MTX use did not reach statistical significance. Within 1 year after miscarriage, the majority of patients who continued trying to conceive achieved a pregnancy resulting in a live birth.