Pharmacologycal use of progesterone and 17-α-hydroxyprogesterone caproate in the prevention of preterm delivery

Preterm delivery (PTD) is defined by the World Health Organization as birth before 37 completed weeks of gestation. In Western countries, PTD accounts for over 75% of all perinatal morbidity and mortality. The social importance of PTD derives from the consideration that it causes near three quarter of neonatal deaths not caused by malformations. Progesterone is a steroid hormone which plays a crucial role in each step of human pregnancy. Early in pregnancy progesterone is produced by the corpus luteum and it is fundamental for pregnancy maintenance until placenta takes over this function at 7-9 weeks of gestation. Late in pregnancy, the role of progesterone is less clear: certainly, it may be importance in maintaining uterine quiescence in the latter half of pregnancy by limiting the production of stimulatory prostaglandins and inhibiting the expression of contraction-associated protein genes (ion channels, oxytocin and prostaglandin receptors, and gap junctions) within the myometrium. In this review, the authors included those controlled clinical studies that have used either 17 hydroxy progesterone caproate (17P), or progesterone (P) or its synthetic derivatives (progestins) in order to avoid or reduce the incidence of preterm delivery, in populations of women at increased risk of preterm birth. The authors conclude that: 1) the treatment with 17P reduces the incidence of PTD in pluriparous women with a previous history of PTD or with recurrent abortion, as well as in nulliparous women with an actual risk; 2) the treatment with P reduces PTD in nulliparous women, namely in the presence of a silent cervical shortening; 3) 17P has no efficacy in multiple pregnancy and it is proven not to have adverse effects on the infants.