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Evidence summaries

Biphasic Versus Triphasic Oral Contraceptives for Contraception

Biphasic and triphasic oral contraceptives may have comparable effects, but there is insufficient evidence from controlled trials. Level of evidence: "C"

A Cochrane review (abstract , review [Abstract]) included 2 studies with a total of 927 patients. The available evidence is limited and of poor quality; the internal validity of these trials is questionable. Given the high losses to follow-up after randomization, these reports may be better considered observational in nature. Given that caveat, the biphasic pill containing norethindrone was associated with inferior cycle control compared with the triphasic pill containing levonorgestrel. This suggests that the choice of progestin may be more important than the phasic regimen in determining bleeding patterns.

Comment: The quality of evidence is downgraded by study quality (inadequate follow up) and by imprecise results (few patients and wide confidence intervals).

    References

    • Van Vliet HA, Grimes DA, Helmerhorst FM, Schulz KF. Biphasic versus triphasic oral contraceptives for contraception. Cochrane Database Syst Rev 2006;(3):CD003283 [Review content assessed as up-to-date: 3 May 2011]. [PubMed]

Primary/Secondary Keywords