First-trimester progesterone does not result in improved live birth rates in women with bleeding in early pregnancy, the PRISM (Progesterone in Spontaneous Miscarriage) trial has found.
Several small studies have suggested that progesterone may improve pregnancy outcomes in women who have bleeding in early pregnancy. However, the large multicentre, randomised, double-blind, placebo-controlled PRISM trial did not find evidence to support the findings.
PRISM recruited 4153 women at 48 hospitals in the UK, who were randomly assigned to vaginal suppositories containing either 400 mg of progesterone (n=2079) or matching placebo (n=2074) twice daily, from the time at which they presented with bleeding through 16 weeks of gestation. The primary outcome was the birth of a live-born baby after at least 34 weeks of gestation.
The percentage of women with available data for the primary outcome was 97 per cent (n=4038).
The incidence of live births after at least 34 weeks of gestation was 75 per cent in the progesterone group and 72 per cent in the placebo group (relative rate, 1.03; 95% CI, 1.00-1.07; P=.08). The sensitivity analysis, in which missing primary outcome data were imputed, resulted in a similar finding. There was also no significant difference between the groups in the incidence of miscarriage or stillbirth. The incidence of adverse events did not differ significantly between the groups.
The findings are published this week in The New England Journal of Medicine.