A condition in which the ovaries stop working and menstrual periods stop before age 40. This can cause fertility problems and symptoms of menopause. There are two types of early menopause, primary and secondary. Primary early menopause means that the ovaries do not function normally. This may be because they have been removed by surgery, or it may be caused by some cancer treatments and certain diseases or genetic conditions. In secondary early menopause, the ovaries are normal but there is a problem getting hormone signals to them from the brain. This is usually caused by diseases of the pituitary gland or hypothalamus. Some women with early menopause sometimes have menstrual periods and may be able to have children. Also called ovarian failure, ovarian insufficiency, and premature menopause.