Combined oral contraceptives (COC) have an oestrogen and a progestogen component. The type of progestogen and/or amount of oestrogen or progestogen can vary per pack of oral contraceptive pills. The objective of this review was to compare currently available low-dose COCs containing different progestogens in terms of pregnancy prevention, bleeding pattern, side effects and discontinuation rates.
Thirty trials were included in this review. All the pills studied were comparable with regard to preventing pregnancy. Women using levonorgestrel-containing pills were less likely to stop taking them than women using norethisterone-containing pills. Women using a gestodene-containing pill experienced less bleeding between periods than women using a levonorgestrel-containing pill but this needs further investigation. There is insufficient good quality evidence to draw any other conclusions.