Pregnancy over the age of 50 has, over recent years, become possible for more women, and more easily achieved for many, due to recent advances in assisted reproductive technology, in particular egg donation. Typically, a woman's fecundity ends with menopause, which, by definition, is 12 consecutive months without having had any menstrual flow at all. During perimenopause, the menstrual cycle and the periods become irregular and eventually stop altogether, but even when periods are still regular, the egg quality of women in their forties is lower than in younger women, making the likelihood of conceiving a healthy baby also reduced, particularly after age 42. The female biological clock can vary greatly from woman to woman. A woman's individual level of fertility can be tested through a var