Immune maladaption between mother and infant has been suggested to induce preeclampsia/eclampsia. When fetuses share more human leukocyte antigen (HLA) types with their mother, immune differences would be limited and thereby could affect this risk. Data from Danish women (1996-2002) with single live-birth pregnancies complicated by severe preeclampsia/eclampsia were compared to women with term pregnancies uncomplicated by hypertension. HLA A, B, and DR types were resolved at the intermediate-level typing (antigen). A total of 201 cases and 195 control mother-infant pairs had complete HLA types. The odds ratios of preeclampsia/eclampsia in mothers sharing both HLA antigens with their infants were 1.19 (95% confidence interval: 0.81-1.76) for HLA A, 0.91 (0.59-1.42) for HLA B, and 1.05 (0.5-1.59) for HLA DR antigens. No specific HLA antigens in either mother or infant appeared important after Bonferroni correction, except possibly DR01 in mothers (protective). Thus, maladaption mediated by adaptive immunity between mother and infant is not the basis for the mother developing preeclampsia/eclampsia.