Many anorexic girls and women either never get their period or their period stops due to extreme weight loss. But for most women menstruation will start up when they begin to gain weight. When a woman's percentage of body fat falls below a certain minimum her body doesn't produce the levels of hormones necessary to stimulate ovulation. Rapid weight loss and undernourishment leads a woman's body into a state of emergency and she will not menstruate if she is just barely surviving. For those women who are able to conceive while suffering from anorexia they seriously jeopardize their own health and the health of their fetus.
Pregnancy presents enormous strain on a woman's body.
As the fetus develops it will take nourishment from the mother. If she suffers from an eating disorder this can seriously deplete her own scant reserves and she may begin to experience the exhaustion and depression that accompany malnourishment. If she brings the pregnancy to full-term she also may lack the energy required to meet the demands of a newborn while remaining healthy herself. Women with eating disorders also have higher rates of miscarriage and an increased risk of giving birth to a low weight baby. Any woman who is struggling with an eating disorder should delay pregnancy until she herself is healthy.