Abstract: The present invention relates to methods for increasing the developmental competence of at least one mammalian germ cell, gamete, zygote, early embryo, implanted blastocyst and/or embryo by administering a compound which is capable of inhibiting the de novo biosynthesis of sterols and thereby establishing cellular conditions that improve their development and survival. The invention also relates to methods for increasing the sterol efflux prior to fertilisation from at least one mammalian ovary, oocyte, female gamete, or ovary derived cell surrounding an oocyte by administering a compound which is capable of promoting the sterol efflux and thereby reducing the phospholipid/sterol ratio of said cells.