AbstractProgesterone appears to be the dominant hormone not only establishing a proper secretory endometrial development but also adequate decidualization to establish pregnancy and sustain pregnancy development. Progesterone is the natural immunoregulator to control the maternal immune system and not to reject the allogeneic fetus. There are two sources of progesterone: corpus luteum first and placenta later. Three progestogens can be used in pregnancy: (i) progesterone (per os, intravaginal and intramuscular), (ii) dydrogesterone (per os), and (iii) 17α-hydroxyprogesterone caproate (intramuscular). There are three indications, for which these progestogens can be clinically used either for treatment or prevention: (i) first trimester threatened and recurrent (habitual) abortion, (ii) premature labor/premature birth, and (iii) pre-eclampsia (hypertension in pregnancy). The available data are limited and only partially randomized. In threatened abortion the use of progesterone, dydrogesterone and 17α-hydroxyprogesterone caproate leads to a significant improved outcome, when at the time of threatened abortion a viable fetus has been ascertained by ultrasound. For prevention of recurrent abortion there are also some data indicating a significant effect compared with women without progestogen treatment. Prevention of preterm birth by progestogens (progesterone vaginally, orally and 17α-hydroxyprogesterone caproate intramuscularly) was significantly effective. The main study groups include pregnant women with a previous history of premature birth. However, also in women with shortened cervix use of progesterone seems to be helpful. The studies done so far in women with risk factors for pre-eclampsia or established pre-eclampsia were based on parenteral progesterone application. However, new studies are urgently needed.
17-alpha Hydroxyprogesterone caproate did not reduce the rate of recurrent preterm birth in a prospective cohort study
