National cohort study of reproductive risk factors for rheumatoid arthritis in Denmark: a role for hyperemesis, gestational hypertension and pre-eclampsia?

While reproductive factors might plausibly be involved in the aetiology of rheumatoid arthritis (RA), the female predominance remains unexplained. A study was undertaken to address the possible impact of live births, pregnancy losses and pregnancy complications on the subsequent risk of RA in a nationwide cohort study.