Continuous oral contraception: changing times.

Oral contraceptives (OCs) remain the most common method of reversible contraception. Despite lowering of oestrogen and progestin content, the same basic design of 21 combination oestrogen plus progestin pills followed by a week of placebo pills has remained. Numerous studies have now documented that the 21/7 regimen needs to be modified. The 7-day hormone-free interval (HFI) in today's low-dose OCs is associated with reduced pituitary-ovarian suppression, allowing for ovarian follicular development, endogenous oestradiol production and possible ovarian cyst formation and ovulation. The 7-day HFI is also associated with hormone withdrawal symptoms that can lead to discontinuation and unintended pregnancy. Modifications in OC regimens are now appearing on the market secondary to the accumulated scientific data on the disadvantages of low-dose 21/7 pills. This article will review the data on problems with standard OC regimens and modifications that can improve the efficacy and side-effect profile.