Pregnancy outcomes in women with rheumatoid arthritis: a retrospective population-based cohort study.

To assess if pregnancies in women with rheumatoid arthritis (RA) are at a higher risk for adverse maternal and neonatal outcomes. A retrospective cohort study was carried out using the Healthcare Cost and Utilization Project - National Inpatient Sample (HCUP-NIS) from the USA. All births that took place from 2004 to 2013 were identified and women were classified as having RA or not on the basis of ICD-9 coding.