Serum from patients with threatened abortion. Effect on in vitro development of mouse embryos.

The effect of serum from patients with threatened abortion on in vitro development of two-cell mouse embryos was evaluated. Embryos were cultured for 72 hours in 7.5% serum supplement from patients with threatened abortion and from women with normal pregnancies and in Ham's F-10 medium with no serum supplement. Significantly fewer embryos developed to the blastocyst stage at 72 hours in the threatened abortion group as compared with the normal pregnancy group and Ham's F-10 (P < .001). These results suggest the presence of serum factors that are toxic to early embryonic development and thus may play a role in the pathogenesis of threatened abortion.