How does the Progestogen Only Pill work?
The Progestogen Only Pill (POP) prevents pregnancy by: • Changing the mucus in the cervix – the mucus in the cervix thickens so that sperm cannot penetrate into the uterus and fallopian tubes to fertilise the egg. The mucus changes occur in all women taking the POP. These changes are effective 48 hours after beginning the pill. • Altering the endometrium – the endometrium (lining of the uterus) changes, making it unsuitable for the egg to implant. • Interfering with the process of ovulation – this happens in up to 60% of women taking the POP and is most common in older women and those who are breastfeeding. Interfering with the process of ovulation takes 7 days of regular pill taking to take effect. These women are more likely to notice irregular or absent periods while on the POP.
