High-risk prematurity--progestin treatment and steroid studies.

Studies have been undertaken regarding the efficacy and modus operandi of 17 alpha-hydroxyprogesterone caproate (17 alpha-OHP-C) in preventing premature labor in high-risk patients. In a total of 70 patients, the treated patient population had a prematurity rate (12.8%) and a perinatal mortality rate (5%) which were significantly lower than those of the total placebo or untreated patient group (40.9 and 25%, respectively). In addition, sequential plasma steroid values were determined in 21 patients, 10 of whom delivered prematurely. The results indicate that low plasma progesterone (P) and 17 alpha-hydroxyprogesterone (17 alpha-OHP) levels precede the onset of preterm labor by weeks. Successful treatment with 17 alpha-OHP-C was characterized by elevated P levels. Plasma estradiol (E2) and cortisol (C) values did not vary with time of delivery or treatment. These findings support the progesterone block theory as an important mechanism affecting preterm delivery in this high-risk population.