Midtrimester pregnancy interruption and the placental progesterone levels.

Placental progesterone contents were studied in 10 patients therapeutically aborted at midtrimester by intraamniotic infusions of hypertonic saline, and from 14 patients (12-20 weeks) aborted by intraamniotic instillation of prostaglandin F-2alpha. The mean S.E. of the progesterone was 1.99 plus or minus 0.07 ug/g. placental tissue in the first group, while with prostaglandin abortion the placental progesterone was 1.45 plus or minus 0.08 ug/g. tissue, which is significantly lower than the results in the first group (P equals 0.001). The possible mechanism of action of prostaglandin as an effective abortifacient is discussed.