Progestogen administration in pregnancy may prevent preterm delivery.

Two recently published meta-analyses of controlled trials of a wide variety of progestational agents, used in pregnancy (Daya 1989; Goldstein et al. 1989), prompted this third meta-analysis of placebo-controlled trials involving the prophylactic use of a single agent, 17 alpha-hydroxyprogesterone caproate. Of seven relevant published reports of controlled trials, six had involved women considered to be a high risk of miscarriage or preterm birth. This analysis provides no support for the view that 17 alpha-hydroxyprogesterone caproate protects against miscarriage, but suggests that it does reduce the occurrence of preterm birth. The latter effect was reflected in a reduced rate of low birthweight babies, but not in a statistically significant reduction in perinatal mortality and morbidity. The difference between this meta-analysis and the two earlier meta-analyses illustrates the problems both of selective sub-grouping and of comprehensive pooling of data from small trials.