Sera from women with histories of repeated pregnancy losses cause abnormalities in mouse peri-implantation blastocysts.

Incubation of peri-implantation mouse blastocysts in the presence of untreated human sera resulted in destruction of the blastocysts. Heating the serum resulted in deactivation of the non-specific toxic factor. Whereas heat-treated serum from women with normal obstetrical histories, and men, supported normal trophoblast attachment and outgrowth, sera from women with reproductive dysfunction resulted in inhibition of attachment or disruption of the trophoblast cells. The inner cell masses were not adversely affected by the sera which were toxic to trophoblast. Fractionation of a serum sample by affinity chromatography resulted in removal of the toxic factor with the IgG fraction. Absorption of the toxic serum with human trophoblast membranes resulted in serum that supported trophoblast outgrowth indicating that the toxic factor was an antibody directed against trophoblast antigens.