[THE FALL AND RISE OF PROGESTERONE PREPARATIONS IN THE PREVENTION OF PRETERM LABOR].

Preterm labor involves about 7.4% of live births in Israel and constitutes over 85% of morbidity and mortality in newborns. Risk factors for preterm labor include a history of preterm delivery shortening of the uterine cervix, cervical procedures, uterine malformations, polyhydramnios, intrauterine growth restriction, preeclampsia, multiple gestations, and more. Progesterone is an essential hormone in the process of fertilization and is involved in the menstrual cycle, implantation and preservation of pregnancy. Due to its various functions in the prevention of preterm labor, the use of progesterone as a preventive treatment has been extensively studied since the second half of the last century and tested in various forms of administration, mainly intramuscular injection and vaginal root. For years, women with a history of preterm labor were treated with intramuscular progesterone once a week between 16 to 36 weeks' gestation or until birth. Recently, vaginal progesterone treatment was initiated in women with cervical length > 25 mm measured by ultrasound between 18-24 weeks gestation. Studies have shown that progesterone treatment reduces the incidence of preterm labor given in the proper indication. This update overview examines progesterone treatment for the prevention of preterm labor.