Abstract
Numerous experimental studies indicate that natural progesterone, through various
mechanisms, exerts an inhibitory effect on uterine contractility and sensitises the
myometrium for tocolytics. It was therefore appropriate to investigate the possible
benefits of oral/vaginal progesterone and the synthetic progesterone derivative 17-α-hydroxyprogesterone
caproate, applied intramuscularly, in clinical studies on primary tocolysis, additively
to established tocolytics (“adjunctive tocolysis”) and as maintenance treatment after
successful tocolysis in cases of threatened preterm birth. Three studies with a small
number of cases do not yield any sufficient evidence for recommending progesterone/17-α-hydroxyprogesterone
caproate as primary tocolysis in women with preterm labour. There is also no evidence
that progesterone or 17-α-hydroxyprogesterone caproate combined with commonly used
tocolytics leads to a prolongation of pregnancy and a significant decrease in the
rate of preterm birth. The data on the use of progesterone as maintenance treatment
is controversial. While randomised, controlled studies with low quality showed promising
results, studies with high quality did not reveal any significant differences with
regard to the rate of preterm birth < 37 weeks of gestation, the latency period until
delivery and in the neonatal outcome between progesterone/17-α-hydroxyprogesterone
caproate and placebo or no treatment. Significant differences in the methodology,
the inclusion and outcome criteria, the mode of application and the dosages of the
substances as well as the inadequate statistical power as a result of low numbers
of cases make interpretation and comparability of the studies difficult. Therefore,
well-designed randomised, placebo-controlled, double-blind studies with uniform primary
outcome criteria are needed in order to clarify whether progesterone and via which
route of administration and at which dosage is of clinical benefit for patients with
manifest preterm contractions and as maintenance treatment after arrested preterm
labour.
Key words
preterm labour - progesterone - 17-α-hydroxyprogesterone caproate - tocolysis - maintenance
treatment/tocolysis