The effects of serum from women with miscarriages on the in vitro development of mouse preimplantation embryos.

It is generally believed that some human miscarriages result from embryotoxic factors existing in the sera. To study the embryotoxicity of such sera, 3.5-day-old mouse blastocysts were cultured for 72 h on 80% sera from different groups of women. After 72 h there was no blastocystic development in 53.2% of the cases grown on sera from women after two or more miscarriages, and none in 33.6% of the blastocysts grown on sera from women after one miscarriage, as compared with 8.2% and 12% respectively on control sera. Sera from women with miscarriages were divided into 'high risk' (50% or more embryotoxicity) and 'low risk' (less than 50% embryotoxicity) sera. The 'high risk' sera from two or more miscarriages caused an average of 72.1% undevelopment, while the 'low risk' sera (less than 50% embryotoxicity) from the same group caused 33.6% undevelopment. The 'high risk' sera from one miscarriage were embryotoxic to 55.8% of the blastocysts and the 'low risk' sera from the same group caused only 8.7% undevelopment. No significant differences were found in the mean serum concentrations of folic acid, zinc and copper of many of the experimental groups, in comparison with controls. The embryotoxic factor/s which exist in the 'high risk' sera from women with miscarriages are still not known.