Skin test reactivity to female sex hormones in women with primary unexplained recurrent pregnancy loss.

The objective was to examine the hypothesis that primary unexplained recurrent pregnancy loss might be associated with an inappropriate immunologically mediated response to progesterone and/or estrogen. This prospective study included 47 women with two or more documented consecutive early pregnancy losses of unknown etiology, and no previous history of deliveries. Intradermal skin testing was performed in the luteal phase of the cycle (days 16-20) using estradiol benzoate, progesterone, and a placebo of refined sesame oil. Immediate (20 min) and late (24h and 1 week) skin test readings for all cases were compared with those of 12 parous women of comparable age with no history of spontaneous miscarriages, premenstrual disorders, pregnancy, or sex hormone-related allergic or autoimmune diseases. Main outcome measure was skin test reactivity to estradiol and/or progesterone. Immediate skin test reactivity to both hormones was observed among half of the cases at 20 min. A papule after 24h, which persisted for up to 1 week, was observed among 32 (68.1%) and 34 (72.3%) cases at the sites of estrogen and progesterone injection, respectively. 55.3% of cases had combined skin test reactivity to both estradiol and progesterone at 1 week. All women in the control group showed absence of skin test reactivity for both estradiol and progesterone at 20 min, 24h, and 1 week. None of the subjects in either group showed skin test reactivity to placebo. There is an association between primary unexplained recurrent pregnancy loss and skin test reactivity to female sex hormones.