During pregnancy, the fetoplacental unit produces large amounts of steroid and peptide hormones: CRH (corticotropin releasing hormone) which increases after eight weeks of amenorrhea up to 100 to 1000 times compared with nonpregnancy values; proopiomelanocortin increases after eight gestational weeks, has a maximum concentration at 20 gestational weeks, and then remains stable until birth [72,73]. Here, CRH is linked to amenorrhea.