The effect of norethindrone and some other synthetic gestagens upon the peripheral plasma levels of progesterone and estradiol during early, human pregnancy.

Abstract

Abstract. Synthetic gestagens were given orally (norethindrone, d‐norgestrel, chlormadinone acetate) or intramuscularly (17α‐hydroxyprogesterone caproate) during 25 early, human pregnancies. The peripheral plasma levels of progesterone and estradiol were determined before, during and after the treatment. Norethindrone was most extensively used and in those women who received this gestagen the peripheral plasma levels of norethindrone were estimated by radioimmunoassay. No consistent effect upon the levels of progesterone or estradiol was observed. In 23 women no vaginal bleeding and no abortion occurred within about a week after the treatment. The pregnancies were terminated surgically. Histological examination of specimens from these abortions revealed no differences on comparison with 10 non‐treated controls. Two women aborted after the treatment, but judging from the hormonal levels these pregnancies were abnormal and would probably have aborted regardless of the treatment.