Background/Purpose:

There are limited data regarding gestational timing of oral corticosteroid (OCS) use during pregnancy and risk of preterm birth. The objective was to compare preterm birth risk in pregnant women with rheumatoid arthritis according to timing of OCS and disease modifying antirheumatic drug (DMARD) use.

Methods:

This study included pregnant women (n=537) with rheumatoid arthritis who enrolled in the MothertoBaby Autoimmune Diseases in Pregnancy Study (2003-2014) before 20 weeks’ gestation. Information on medication use and pregnancy characteristics was collected by telephone interview at up to 3 time points during pregnancy and once after delivery, plus by medical record review. Exposures were classified into mutually exclusive groups: neither OCS nor DMARD (reference) OCS only, DMARD only, and both OCS and DMARD according to any use during the 1st trimester, 2nd trimester, and 90 days prior to gestational week 37 or delivery date, whichever occurred first. Modified Poisson regression was used to estimate relative risks (RR) and 95% confidence intervals (CI) between exposure and preterm birth, with separate models for each exposure window. Models were adjusted for year, maternal age, race/ethnicity, socio-economic status, overweight, autoimmune comorbidities, multiple gestation, nonsteroidal anti-inflammatory drug use, Health Assessment Questionnaire (HAQ) score at enrollment, and gestational age at enrollment.

Results:

During pregnancy, 55% of women used OCS (of which 98% used prednisone), 68% used biologics, and 31% used non-biologic DMARDs. Median HAQ score at enrollment was 0.25 for neither OCS nor DMARD, 0.38 for OCS only, 0.25 for DMARD only, and 0.5 for OCS and DMARD use in the 1^st trimester. Preterm birth risk was 6% in women who did not use OCS or DMARD during the 1st trimester, and the adjusted RR was 3.3 (CI: 1.1-9.5) for 1^st trimester OCS, 1.7 (CI: 0.6-4.7) for DMARD, and 3.1 (CI: 1.2-8.0) for DMARD and OCS. Preterm birth risk was 13% in women who did not use OCS or DMARD during the 2nd trimester, and the adjusted RR was 1.5 (CI: 0.9-2.5) for 2nd trimester OCS, 0.6 (CI: 0.3-1.2) for DMARD, and 1.5 (CI: 0.9-2.6) for DMARD and OCS. Preterm birth risk was 11% in women who did not use OCS or DMARD in the 90 days before delivery or gestational week 37, and the adjusted RR was 1.8 (CI: 1.1-3.1) for OCS, 0.8 (CI: 0.4-1.7) for DMARD, and 1.9 (CI: 1.1-3.4) for DMARD and OCS.

Conclusion:

Early and late pregnancy OCS use with or without DMARD use was associated with an increased risk of preterm birth compared with women who did not use OCS or DMARD. DMARD use alone was not associated with an increased risk of preterm birth. The OCS and preterm birth association was strongest for 1st trimester use partly due to low preterm birth risk in the 1^st trimester reference group. Results may reflect residual confounding by RA severity.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/oral-corticosteroid-use-during-pregnancy-and-risk-of-preterm-birth-in-women-with-rheumatoid-arthritis/