The objective of the present investigation was to assess the effectiveness and acceptability of high dose conjugated estrogen (Premarin) as an interceptive for use in every-day clinical practice.
Subjects were accepted for the study if (a) they had had a single episode of midcycle unprotected intercourse and presented for treatment within 72 hours of exposure and (b) had a negative pregnancy test and no clinical signs of pregnancy. Patients who met the above criteria were treated with oral conjugated estrogens (Premarin) 10 mg. thrice daily for five consecutive days.
Of 551 women requesting post-coital contraception only 377 met the necessary criteria and were thus treated. Of these, 359 (95.2 per cent) completed the six weeks of study as outlined above. Only 2 of the 18 defaulters were lost to follow-up. The remainder included patients who had menstruated before their scheduled visit and did not return as requested, or who did not take the medication as directed but were not found to be pregnant at their six-week examination. All were contacted and examined and were found not to be pregnant.
The results of this study are, therefore, based on the 359 women who met and completed all the criteria of the study. Only one subject became pregnant-a pregnancy rate of 0.3 per cent.
Although most of the patients reported some side effects, the degree of discomfort was usually mild and interfered with the daily activity of only 51 subjects. Of the side effects, nausea was the most commonly reported complaint (52.4 per cent) but this too was usually mild in nature and in many instances did not even warrant the taking of an anti-emetic. The anti-emetic, Compazine, was prescribed for patients complaining of nausea and vomiting. Just over half of the subjects (52.3 per cent) required some medication.
The next most common group of side effects appeared to be related to a transient fluid retention as manifested by a gain of weight in excess of three pounds (25.8 per cent), breast tenderness (37 per cent) and enlargement (26.5 per cent) and headache (23.8 per cent). The latter could, of course, have been attributed to numerous other factors and may not reflect a direct cause and effect relationship. Twenty subjects (5–6 per cent) reported leg cramps, while one subject had a suspected episode of superficial phlebitis.
Despite the large concentrated five-day course of estrogen, very few women reported a significant alteration in the duration of their subsequent menses. An earlier than expected onset occurred in 18.9 per cent, while 12.8 per cent reported a later onset of their period. The “character” and bleeding pattern of their first period was reported to be “different” in about one-third (31.7 per cent) of the subjects.