Since the recent publication of our study on the comparative effectiveness of combined oral contraceptives (COCs) in relation to progestogen type, length of pill-free interval and body mass index (BMI) during typical clinical use,1 we have received requests for further information. Specifically, we were asked if adolescents, who are known to have higher missed pill rates and thus higher unintended pregnancy rates, specifically benefit from shortening the pill-free interval. In our study this specifically refers to a shortening of the pill free interval to 4 days compared to the conventional 7-day intake break.

First, we would like to summarise the main study results then provide specific data for adolescents. In the …