[Anti-nidation activity of oral contraceptives]

The antinidatory activity of the oral contraception is generally unknown: the contraceptive pill mainly prevents the gametes from meeting. However, pregnancies under pill indicate conception of embryos. Besides, missed pills protocols sometimes record ovulatory escape. We suggest the computation of an Embryo Destruction Index (EDI), in order to measure the antinidatory effect of two categories of oral contraceptives: combined estroprogestatives and microprogestatives.