Clinical trial of a combination of lynestrenol and mestranol (Lyndiol) as an oral contraceptive agent.

Contraception with lynestrenol-mestranol (Lyndiol) was studied in 332 Mexican women during a period of two and one-half years. Side effects were minimal or transient. No pregnancies occurred in those who took the medication according to instructions. The women were followed with yearly pelvic examinations and Papanicolaou smears, serial endometrial biopsies and extensive studies of blood, liver and glandular function. Complete ophthalmological studies were done on 30 patients. No clinical or laboratory evidence of harmful effects could be demonstrated. Return to ovulation (using pregnanediol excretion and endometrial biopsies as parameters) occurred in all of 22 women studied in the first three post-treatment cycles. Eight posttreatment pregnancies and the resulting offspring were normal. The first post-treatment cycle, as with other oral contraceptives, was unpredictable and tended to be prolonged. It varied in length from 22 to 60 days.