Spontaneous labor onset: is it immunologically mediated?

OBJECTIVE

The investigators tested the hypothesis that maternal-fetal immune interactions could be important in initiating spontaneous labor onset by examining if labor was delayed when fetuses share maternal HLA antigen types.

STUDY DESIGN

HLA antigen types A, B, and DR in 200 Danish mother-infant pairs delivering in 42-44 weeks (postterm) were compared with 195 mother-infant pairs delivering in 37-40 weeks (term).

RESULTS

Sharing of HLA A and B antigens was more common than expected in postterm deliveries. Odds ratios were 1.54 (95% confidence interval [CI], 1.01-2.35) and 1.75 (95% CI, 0.87-3.52), respectively (risk per shared antigen: 1.40 [95% CI, 1.04-1.90] per unit increase). Adding stringent birth-length criteria for postmaturity (92 cases; 168 controls) strengthened risks associated with antigen sharing to 1.57 (95% CI, 0.90-2.74) and 2.60 (95% CI, 1.15-5.88), respectively (risk per shared antigen: 1.60 (95% CI, 1.10-2.32).

CONCLUSION

Postterm-delivered infants had more HLA A and B antigens in common with their mothers, suggesting that recognition of HLA antigen differences by adaptive immunity may have a role in triggering labor onset.