The Endocrinology of Human Parturition

Definitive modifications of the endocrine milieu of pregnancy herald the onset of parturition in many mammalian species. It is understandable, therefore, that much research has been conducted to examine the role of the sex steroid hormones in the maintenance of human pregnancy, the initiation of parturition, and thence the onset of labor. The endocrine changes that accompany human pregnancy are massive; indeed, it is not generally appreciated that the hormonal modifications that obtain in women during gestation are much greater and, in many respects, more diverse than those in all other mammalian species studied, including subhuman primates. In spite of these endocrine alterations in human pregnancy and notwithstanding recognized hormonal changes that precede parturition in most mammals, the endocrine changes in human pregnancy that participate in the initiation of parturition, if such exist, have not been discovered.