Introduction Female genital mutilation (FGM) harms women’s health and well-being and is widely considered a violation of human rights. The United Nations has called for elimination of the practice by 2030.

Methods We used household survey data to measure trends in the prevalence of FGM in 22 countries. We also examined trends in the severity of the practice by measuring changes in the prevalence of flesh removal, infibulation and symbolic ‘nicking’ of the genitals. We evaluated the extent to which measurement error may have influenced our estimates by observing the consistency of reports for the same birth cohorts over successive survey waves.

Results The prevalence of all types of FGM fell in 17 of 22 countries we examined. The vast majority of women who undergo FGM have flesh removed from their genitals, likely corresponding to the partial or total removal of the clitoris and labia. Infibulation is still practised throughout much of sub-Saharan Africa. Its prevalence has declined in most countries, but in Chad, Mali and Sierra Leone the prevalence has increased by 2–8 percentage points over 30 years. Symbolic nicking of the genitals is relatively rare but becoming more common in Burkina Faso, Chad, Guinea and Mali.

Conclusion FGM is becoming less common over time, but it remains a pervasive practice in some countries: more than half of women in 7 of the 22 countries we examined still experience FGM. The severity of the procedures has not changed substantially over time. Rigorous evaluation of interventions aimed at eliminating or reducing the harms associated with the practice is needed.