Specific risk factors are not known at this time. Studies found more women than men reporting the hair loss but there could be other reasons for this such as: 1) Men may not report hair loss as often as women because they typically wear their hair shorter, and hair loss may not be as noticeable as it would be in women with longer hair. In addition, some men expect to lose their hair as they age (e.g. male pattern baldness). 2) Women and health care workers who reported hair loss are more in touch with their health care providers about health concerns.
Source: Centers for Disease Control and Prevention