The MIxS description of menarche is unconventional

[turbomam]

"Date of most recent menstruation" is not compatible with wikipedia's

Menarche (/məˈnɑːrki/ mə-NAR-kee; from Ancient Greek μήν (mēn) 'month' and ἀρχή (arkhē) 'beginning') is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility. Girls experience menarche at different ages.[1][2] Having menarche occur between the ages of 9–14 in the West is considered normal.[3]

[turbomam]

https://en.wikipedia.org/wiki/Menarche