Accuracy of Menstrual History for Determining Gestational Age Among Adolescents Who Underwent Abortion in England and Wales

Menstrual dating provides high sensitivity for identifying adolescents as ineligible for no-test medication abortion, with very low risk of clinically important misclassification. Adding menstrual history indicators improves sensitivity but indicates unnecessary scans for many eligible individuals. Policy must balance the rare risk of misestimation against costs of restricting adolescents' access, where disproportionate care barriers already exist.