Abstract IgD levels were determined in maternal sera (obtained at delivery) at different stages of gestation, and found to be low in premature deliveries but normal in term deliveries when compared to those of normal nonpregnant women. Maternal IgD levels at delivery revealed a significant exponential correlation with duration of pregnancy. These results are at variance with the results of other surveys. The discrepancy could be explained on ethnic or methodological grounds. No correlation was found between maternal IgD levels and the degree of HL-A disparity between mother and product. Specificities HL-A-2 and HL-A-13 in the mother revealed a discrete correlation with IgD levels at delivery.