To investigate the influence of pregnancy and postpartum on rheumatoid arthritis (RA) course and the impact of maternofetal HLA class II disparity.

In 13 women with RA, disease activity was assessed prospectively, before and every three months throughout pregnancy and after delivery until one year in postpartum. The HLA class II disparity was evaluated by typing HLA–DRB1, DQB1 and DQA1 alleles by the PCR-SSOP for 12 couples mothers and babies. Furthermore, for three women, RA disease activity during a previous pregnancy was evaluated retrospectively and HLA typing was performed for the three children.

The mean age of patients was 30±5years. All women had successful pregnancy. During pregnancy, a favourable RA outcome was noted in 62.5% of cases. Three patients were in remission after conception. Persistent disease activity was noted in 30% of cases. In postpartum, disease relapse occurred in 92% of cases at a mean delay of 80±63days. Three women did not resume the initial modifying antirheumatic drugs (DMARDs) 12months after delivery. For others, the mean delay was 6±3.5months. There was no significant correlation between the clinicoradiological parameters and the RA outcome. We noted a tendency towards correlation between male newborns and an unfavourable RA outcome (p=0.059). A high degree of maternofetal disparity in HLA class II was seen in 73.5% of cases. We observed a more marked improvement in disease activity parameters in case of more than one disparity but without a significant statistical difference.

A favourable RA outcome during pregnancy in about two-thirds of the cases and a frequent relapse after delivery were observed. RA activity improvement is more obvious at the end of pregnancy. A high degree of maternofetal HLA class II disparity seems to modulate RA disease activity.