Menstrual Hygiene Day Menstrual Hygiene Day Menstrual Hygiene Day (MHD, MH Day in short) is an annual awareness day on May 28 to highlight the importance of good menstrual hygiene management (MHM). It was initiated by the German-based NGO WASH United in 2014 and aims to benefit women and girls worldwide. The 28th was selected to acknowledge that 28 days is the average length of the menstrual cycle. In low-income countries, girls’ choices of menstrual hygiene materials are often limited by the costs, availability and social norms. Adequate sanitation facilities and access to feminine hygiene products are one part of the solution. Creating
Tzolk'in agricultural cycle of highland Guatemala, which is also about 260 days. Aveni notes that "the average duration between successive halves of the eclipse season, at 173 ½ days, fits into the tzolkin in the ratio of 3 to 2." This may seem contrived, but the Maya did employ the tzolkin to predict positions of Venus and eclipses. Another theory is that the 260-day period is the length of human pregnancy. This is close to the average number of days between the "first missed" menstrual period and birth, unlike Naegele's rule which is 40 weeks (280 days) between the "last" menstrual