Double-blind controlled trial of progesterone substitution in threatened abortion.

Between 1983 and 1984 a double-blind randomized study with progesterone substitution in threatened abortion was carried out. Fifty-six patients with vaginal bleeding during the first trimester of pregnancy, the internal cervical os being closed, were referred to the hospital. Twenty-five women (5th and 6th week of gestation) with positive serum concentrations of beta-hCG were admitted to the study without regard to sonogram results. In other 25 women (7th-10th week of pregnancy) and 6 women (greater than or equal to 11th week of pregnancy) fetal heart action and movement could be demonstrated by ultrasound. The patients were prescribed bed rest and vaginal suppositories twice daily, containing either 25 mg progesterone or only polyethylene glycol. The code was not broken until after completion of the study. Serial serum determinations of beta-hCG, estradiol-17 beta (E2), progesterone, and ultrasound were performed. Four patients had to be omitted from final analysis (two tubal pregnancies, one intrauterine infection, one sectio parva). Three of 26 patients progesterone (11%) and five of 26 patients with placebo (19%) had an abortion, which represented no significant difference. Frequency of abortion was increased in women more than 30 years old, in women with previous abortions and after ovulation induction. Progesterone treatment resulted in a significant elevation of serum progesterone concentrations (p less than 0.01), while beta-hCG and E2 were unchanged. The results of this study confirm that pregnancy outcome is favorable in women with bleeding and normal hormone concentrations without hormonal treatment and unfavorable in women with reduced beta-hCG and E2-concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)