In industrialized countries, such as the United States, South Korea, and parts of Western Europe, the average age for menarche is generally between 12 and 13 years, although it can occur as early as 8 and as late as 16 or 17.
Tādās industriālās valstīs kā ASV, Dienvidkoreja un daudzas Rietumeiropas zemes meitenēm mēnešreizes vidēji sākas 12 līdz 13 gadu vecumā, tomēr dažreiz tas notiek jau 8 vai arī tikai 16 vai 17 gadu vecumā.