It is clear that suckling is the critical inhibitory signal (Tsukamura & Maeda 2001), and the principle cause of infertility is an almost-complete suppression of the pulsatile secretion of GnRH from the hypothalamus, the consequent loss of pituitary gonadotropin secretion and ovulation failure (Fox & Smith 1984). This evidence concerns the gene GNRH1 and Infertility.