The Washington Post cited a 2009 paper published in the American Economic Journal: Applied Economics in an article about a proposed law in Italy to offer “menstrual leave” for working women. In the paper, co-authors Andrea Ichino and Enrico Moretti studied personnel data from a large Italian bank and found that absences of women below the age of 45 followed a 28-day cycle, which they interpreted as evidence that the menstrual cycle increased female absenteeism. They also said it helped explain at least 14 percent of the earnings gap between men and women.