The association between gravidity, parity and the risk of developing rheumatoid arthritis: A systematic review and...

To establish if gravidity and parity associate with the development of rheumatoid arthritis (RA), and to establish if this effect is influenced by the time elapsed since pregnancy/childbirth, the number of pregnancies/childbirths, and serological status, through systematically reviewing the literature and undertaking a meta-analysis.

We searched Medline/EMBASE (from 1946 to 2018) using the terms "rheumatoid arthritis.mp" or "arthritis, rheumatoid/" and "pregnancy.mp" or "pregnancy/" or "parity.mp" or "parity/" or "gravidity.mp" or "gravidity/" (observational study filter applied). Case-control/cohort studies that examined the relationship between parity/gravidity and the risk of RA in women were included. Studies reporting effect size data for RA in ever vs. never parous/gravid women as ORs/RRs with 95% confidence intervals were included in a meta-analysis. Other relationships (i.e. risk by pregnancy/childbirth numbers) were analysed descriptively.

Twenty studies (from 626 articles) met our inclusion criteria, comprising 14 case-control (4799 cases; 11,941 controls) and 6 cohort studies (8575 cases; 2,368,439 individuals). No significant association was observed in the meta-analysis of studies reporting the risk of RA in ever vs. never parous women (OR 0.91; 95% CI 0.80-1.04) and ever vs. never gravid women (OR 0.86; 95% CI 0.46-1.62). No consistent evidence of a relationship between the number of pregnancies/childbirths and RA risk was seen. No significant association was observed between being pregnant, or in the immediate post-partum period, and the risk of developing RA.

Our systematic review does not support the concept that gravidity and parity are associated with the risk of RA development.