
There’s vast variation in women’s cycles, and even the experts don’t agree on the terminology that best describes a normal versus an abnormal menstrual cycle.
But a 2007 study in the journal Human Reproduction, a collaboration between the OB-GYN departments at UCLA, the University of Sydney in Australia, and the University of Edinburgh in the United Kingdom, reported that a normal cycle can be anywhere from 24 to 38 days long with bleeding lasting 4 1/2 to 8 days. Yours doesn’t fall within these parameters? Ask your doctor whether there’s cause for concern.
For more fertility tips, check out Conceive's book, Fertility Facts: Hundreds of Tips for Getting Pregnant.
