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Continuous oral contraception: changing times

https://doi.org/10.1016/j.bpobgyn.2007.08.004Get rights and content

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.

Section snippets

Drawbacks of the 21/7 regimen

While 21/7 OCs have been the mainstay over the 45-year history of the pill, reductions in dosage have led to a need to redesign the standard regimen with a focus on modifications in the 7-day HFI.

Modifying the 21/7 OC Regimen

OC regimens that extend the active pill interval beyond the conventional 21 days have been used for more than 20 years.22, 23, 24 However, prior to the introduction of a 91-day extended-regimen product in the USA in 2003, use of an extended regimen required creative prescribing on the part of healthcare providers with instructions on how to modify their 21/7 pill pack by eliminating the 7-day HFI and going immediately into the next packet of pills.

Newer OC regimens approved for use have

Reduction in menstrual bleeding

The duration and blood loss during scheduled (hormone withdrawal) bleeding after an extended cycle of hormonal contraception is of no greater duration or severity than blood loss experienced after 28-day cycles. For example, the median number of days of scheduled bleeding per episode was 2.5 days with the 91-day regimen and 2.8 days with the 28-day cycle in a comparative study of a 91-day OC regimen.27 Therefore, over a comparable 3-month study period, the 28-day cycle user would potentially

Patient preference

Changes in reproductive patterns such as marrying later, having fewer children and shorter intervals of breastfeeding has left modern women with many more menstrual periods than their predecessors.54 The resulting increased number of menstrual cycles over a lifetime has not been welcomed by all women. Monthly menstruation in women of reproductive age is necessary unless the patient is pregnant, using hormonal contraception, breastfeeding or has undergone hysterectomy.

Menstrual disorders are the

Safety of extended regimens

When the published data regarding extended regimens are examined in total, the safety profile is virtually the same as for 21/7 cycles. Despite concerns that extended cycles provide more cumulative oestrogen exposure over a month, adverse event profiles with extended cycles have been comparable to that reported with the conventional regimen. The safety of 91-day regimens has been demonstrated in both 1-year trials and longer-term 2-year studies.27, 28, 34

Metabolic changes, such as blood glucose

Summary

Oral contraceptives are the most common method of reversible contraception and have provided women with many non-contraceptive benefits. With the reduction in hormone content over the past few decades, the standard 7-day HFI has been shown to lead to unacceptable pituitary–ovarian escape leading to follicular development, endogenous oestradiol production, and possible ovarian cyst formation and ovulation. Hormone withdrawal symptoms as a result of the 7-day HFI can lead to discontinuation and

Acknowledgements

The author would like to thank Kathryn Martin for her invaluable assistance with this manuscript.

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