Percival‐Smith 1990.

Methods	Randomized controlled trial with blinding (of investigator). The method of randomization and the use of allocation concealment are not described.
Participants	469 women at 4 Canadian sites who were aged 15 to 35 years. However, only 391 women were admitted to the study and used the pills for at least one month.
Interventions	Biphasic norethindrone plus EE (NET 500‐1000 μg and ethinyl estradiol 35 μg in a 10/11 day regimen) (Ortho 10/11) versus triphasic levonorgestrel plus EE (LNG 50‐75‐125 μg and EE 30‐40‐30 μg in a 6/5/10 day regimen) (Triphasil) versus triphasic norethindrone plus EE (NET 500‐750‐1000 μg and EE 35 μg in a 7/7/7 day regimen) (Ortho 7/7/7).
Outcomes	Primary outcomes measures were side effects, cycle control, continuation, discontinuation rates, and reasons for discontinuation.
Notes	The report provides an a priori hypothesis and an adequate sample size calculation. 169 women discontinued, but the reasons for discontinuation are unclear. Intermenstrual bleeding is breakthrough bleeding and spotting. Continuing menstrual flow is not included in the intermenstrual bleeding data.

EE = ethinyl estradiol