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

Objective. Studies indicate that maternal-fetal incompatibility of HLA-DR and DQ antigens may be associated with a decreased risk of disease activity during pregnancy in women with rheumatoid arthritis. We attempted to replicate these findings in a large cohort of women with inflammatory polyarthritis. Methods. Women with an inflammatory polyarthritis were recruited during the last trimester of pregnancy and were intel viewed and examined in their homes by a research nurse. Each woman provided a sample of blood as well as permission 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 typing performed. On the basis of known haplotypes found in Caucasian populations. 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 incompatibility 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 ratio 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 HLA incompatibility contributes to remission of inflammatory arthritis during pregnancy.