Incidence of side effects with contraceptive placebo.

The incidence of undesirable side effects during hormonal oral contraceptive therapy has varied considerably according to different investigators. A study given a placebo tablet was carried out in 147 women during 424 months of observation. Pregnancy rate was 203. Only 76.8 per cent of the cycles have a length between 25 and 35 days, and intermenstrual bleeding occurred in 5.8 per cent of the cycles. Out of 39 endometrial biopsies 17.9 per cent show anovulatory cycles. A large variety of side effects were reported in 66.8 per cent of the months, the most frequent being decrease in libido, headache, pain and bloating in lower abdomen, and dizziness. In conclusion, psychogenic factors play an important role in the production of side effects in women taking oral contraceptives. © 1969.