RESUMO
There is a growing awareness of a need for developing novel methods of contraceptive technology which should not only be effective in providing protection against conception but also take into consideration the reproductive health issues confronting men and women. This paper considers the process of embryo implantation as one such potential target. The hormonal basis of embryo implantation in primates has been discussed to indicate that progesterone, and not estrogen, from ovarian source is the primary determinant of embryo-endometrial maturation and their synchronization for implantation. Thus, low dose administration of the anti-progesterone, mifepristone, during early luteal phase has been shown to be an effective anti-implantation approach to for fertility control. Furthermore, the dissociation of endometrial-hormonal synchrony at the time of blastocyst implantation following the post-ovulatory mifepristone administration has been shown to be the physiological basis of its anti-implantation effect with undisturbed circulatory hormone profiles and ovarian functions. Further studies are required to appreciate the full potential and to mollify the limitations of this approach.