A meta-analysis of randomized control trials of progestational agents in pregnancy.

The continued use of progestational agents in attempts to achieve a normal outcome of pregnancy in women with a 'high-risk' pregnancy (previous miscarriage, stillbirth or present preterm labour) prompted this meta-analysis of randomized control trials of such therapy. Of 20 trials of a progestogen 15 had combinable data. Combined comparisons, using odds ratios with confidence intervals, were made of the rates of livebirths at term or preterm and the sum of term and preterm deliveries, miscarriages, stillbirths and neonatal deaths. All but one comparison failed to show a significant benefit. Only the preterm delivery versus the term delivery comparison approached statistical significance. There were average deficiencies of quality apparent in the studies, and a test for heterogeneity among the studies was positive, but these caveats do not diminish the conclusion that progestogens should not be used outside of randomized trials at present. If trials are done, they should include only women with demonstrated hormonal abnormalities who are carrying a live fetus as shown by ultrasonography.