Maternal-fetal HLA incompatibility and the course of inflammatory arthritis during pregnancy

Objective. Studies indicate that maternal-fetal incompatibility of HLA-DR a nd DQ antigens may be associated with a decreased risk of disease activity during pregnancy in women with rheumatoid arthritis. We attempted to replic ate these findings in a large cohort of women with inflammatory polyarthrit is. Methods. Women with an inflammatory polyarthritis were recruited during the last trimester of pregnancy and were intel viewed and examined in their ho mes by a research nurse. Each woman provided a sample of blood as well as p ermission for a sample of cord blood to be taken at the time of birth. DNA was extracted from both maternal and cord blood and HLA-DRB1 and DQB1 typin g performed. On the basis of known haplotypes found in Caucasian population s. DQA1 type was inferred wherever possible. Results. Based on 110 or more maternal-feral pairs, there was no increased occurrence of disease remission associated with maternal-fetal incompatibil ity of DRB1 alleles (remission ratio 0.7, 95% confidence interval 0.2-2.8), DQB1 alleles (remission ratio 1.2, 0.3-6.5), or DQA1 alleles (remission ra tio 0.8, 0.3-1.9). Results were similar whether maternal-fetal sharing was defined by broad allelic group or by specific alleles. Conclusion. Our results do not support the hypothesis that maternal-fetal H LA incompatibility contributes to remission of inflammatory arthritis durin g pregnancy.