Progestogen Only Pill
Progesterone Only Pill (POP) is a daily oral contraceptive, taken without a pill-free break. It acts by thickening the cervical mucus, thinning the endometrium and reducing motility of the cilia in the fallopian tubes. It often prevents ovulation (especially DSG, up to 97% inhibited, compared to 60% for the other POPs).
POPs available in the UK include desogestrel (DSG) 75μg (Cerazette, Cerelle), norethisterone (NET) 350μg (Micronor, Noriday), and or levonorgestrel (LNG) 30μg (NorgestonR). If used correctly POP has a 99% efficiency. DSG is potentially more effective as it has more impact on ovulation inhibition, and a longer missed pill window.