Oral contraceptives containing oestrogen and progestagen in high dosage may produce many undesirable side effects. The risk of thrombo-phlebotic episodes (Vessey & Doll, 1969) has caused much concern, but the possible long-term effects of the numerous metabolic changes have also to be considered. Amongst the latter, impaired glucose tolerance (Wynn & Doar, 1969) and increased levels of serum glutamic—pyruvate transaminase (SGPT) have been reported (Larsson-Cohn, 1965).
The use of norgestrel alone, given continuously in low dosage of 50 μg, is slightly less effective as a contraceptive than conventional combinations of oestrogen and progestagen (Foss, Svendsen, Fotherby & Richards, 1968) and 22% of cycles are shorter than 23 days in the women on this regimen, but the incidence of side effects is much lower (Foss, 1968). With the elimination of the