*3.6.1 Side-effects*

• Bleeding—Altered bleeding patterns are a common reason given by women for stopping POPs [62–64]. Indeed, almost half of POP users experience prolonged bleeding and up to 70% report breakthrough bleeding or spotting in 1 or more cycles [64]. Bleeding patterns associated with POPs may depend upon the type of progestogen used, the dose at which it is given, circulating endogenous estradiol concentrations, and ovulation.

