Human reproduction
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Mifepristone (RU 486) is an antiprogestin which interacts with progesterone at the receptor level. Administration of mifepristone immediately after ovulation does not upset the menstrual cycle. However, the maturation and function of the endometrium is inhibited and uterine contractility is changed. ⋯ On the basis of the time of the LH peak, it was retrospectively calculated that in 124 cycles at least one act of intercourse occurred during the period 3 days before to 1 day after ovulation. The probability of pregnancy in this period of the menstrual cycle is thus 0.008. The women did not complain of any treatment-related side-effects apart from slight bleeding for 2-3 days starting a few days after the day of treatment in 35% of the cycles.(ABSTRACT TRUNCATED AT 250 WORDS)