Glasier A, Baird D T
Baillieres Clin Obstet Gynaecol. 1990 Jun;4(2):283-91. doi: 10.1016/s0950-3552(05)80227-5.
It is possible to prevent pregnancy after unprotected intercourse by suppressing ovulation, inhibiting fertilization or interfering with tubal transport and/or implantation of the early embryo. IUCDs probably prevent implantation by stimulating the release of prostaglandins from the endometrium but are not acceptable to many women. Post-coital contraceptive steroids, e.g. high-dose oestrogens, are associated with a relatively high incidence of side-effects and must be taken within 72 hours of coitus. As these agents are effective by creating a uterine environment unfavourable for implantation, it may be possible to use antigestagens or antioestrogens in this way. It is already known that an antigestagen in combination with a prostaglandin is a highly effective method of inducing abortion in very early pregnancy. The corpus luteum is essential for the maintenance of pregnancy and its destruction by a luteolytic agent should dislodge the implanting embryo. If an effective method of preventing implantation could be developed which was relatively free from side-effects, it should be possible to use it as a regular form of contraception to be taken only when the risk of pregnancy had occurred.
通过抑制排卵、阻止受精或干扰输卵管运输及/或早期胚胎着床，可以在无保护性交后预防怀孕。宫内节育器可能通过刺激子宫内膜释放前列腺素而阻止着床，但许多女性对此并不接受。性交后避孕类固醇，如大剂量雌激素，副作用发生率相对较高，且必须在性交后72小时内服用。由于这些药物通过营造不利于着床的子宫环境而发挥作用，因此有可能以这种方式使用抗孕激素或抗雌激素。已知抗孕激素与前列腺素联合使用是在妊娠极早期诱导流产的一种高效方法。黄体对于维持妊娠至关重要，用溶黄体剂破坏黄体应能使着床的胚胎排出。如果能研发出一种相对无副作用的有效预防着床的方法，那么就有可能将其用作仅在有怀孕风险时服用的常规避孕方式。
