Human Relaxin Genes in the Decidua and Placenta

Abstract

It is now generally accepted that the endocrine events of human parturition are different from those in animal models of parturition. The lack of obvious systemic endocrine changes in late pregnancy in the human led to the hypothesis that the events involved are predominantly localized within the uterus (1, 2). The research focused on the prostaglandins that fulfilled the criteria of local production and action and were clearly involved in parturition as judged by exogenous administration. Although of major value in the clinical setting, it became clear that the stimulation of prostaglandin production was not the starting point of human peripartal changes. Interestingly, a similar conclusion has recently been reached for another group of locally produced and acting intrauterine bioactive agents, the cytokines: “The accumulation of bioactive agents characteristic of the inflammatory response in amniotic fluid during term and preterm labor is an accompaniment of parturition and not its cause (3).” This does not mean that these substances have no role in cell:cell signaling in the early stages of parturition since the end points in each case have been the macrodetermination of high levels as “overspill” into amniotic fluid.