A period that lasts for only two days is considered on the low end of the spectrum, but is still thought of as normal and does not necessarily constitute a medical concern, according to Cleveland Clinic. The most common period duration is between three and five days.
Each woman has a different cycle according to the natural hormonal fluctuations that occur within her body each month to prepare for a possible pregnancy, notes Cleveland Clinic. The main concern regarding a woman's menstrual cycle is not the length but the regularity, explains Everyday Health. As long as a woman maintains the same average period length each month, she should accept this as her regular pattern.
Some woman may lack the necessary estrogen required to produce a thick uterine lining, causing lighter menstrual bleeding. Shorter periods are common in young girls who are entering puberty and do not yet have high levels of estrogen. Women entering menopause experience drops in their hormone levels, and this causes their periods to become shorter than usual. There are times when a short period signals a health problem such as ectopic pregnancy, especially if diminished bleeding is out of the ordinary. Some forms of birth control are designed to thin the uterine lining, resulting in shorter periods, notes Everyday Health.