The relationship between post-onset pregnancy and functional outcome in women with recent onset inflammatory polyarthritis: results from the Norfolk Arthritis Register

OBJECTIVE: To examine the influence of post-symptom-onset pregnancy on disease outcome in women with inflammatory polyarthritis (IP). METHODS: A total of 631 women, aged <48 years at symptom onset, were registered with the Norfolk Arthritis Register (NOAR) between 1990 and 2004. Functional disability was assessed using the Stanford Health Assessment Questionnaire (HAQ). Blood was tested for rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (ACPA). The date and outcome of all pregnancies were reported during a median follow-up of 7 years. Linear random effects models were used to examine HAQ score over time, by pregnancy status. Results were then stratified for RF and ACPA status. RESULTS: In all, 72 women had a post-onset pregnancy (Po-P) including 45 women who were pregnant at a follow-up assessment. Pregnancy was generally associated with lower HAQ scores over time than non-pregnancy. The 10 ACPA-positive women who had a Po-P had significantly worse subsequent HAQ scores. CONCLUSION: Overall, Po-P is associated with lower HAQ scores, compared to no Po-P. This may reflect a beneficial effect of pregnancy on disease outcome, or that predominantly women with milder disease become pregnant. In women with the worst predicted outcome (APCA positive), Po-P is associated with a worse outcome than no pregnancy.