'Patient failure' as a reliability model for the 'minipill': a clinical study

A trial was carried out in 10 healthy women to study the effects of withdrawal of treatment with 0.5 mg lynestrenol per day, for 3 successive days during the pre-ovulatory phase, on the physiological properties of the cervical mucus, vaginal cytology and pituitary and ovarian functions. In most cases, the amount, Spinnbarkeit and ferning of the cervical mucus and sperm penetration remained the same as that before interruption of treatment. In 2 women, the ferning altered to 'good' for 2 to 3 days as the amount of mucus increased slightly. Spinnbarkeit increased at the same time and sperm penetration was good. The changes in LH and FSH excretion suggested that ovulation possibly took place in 1 of the women studied. A mid-cycle oestrogen peak was seen in 2 women. No side-effects were reported during the study apart from irregular intermenstrual bleeding in 1 woman.