For those women who have not been contraceptively sterilized, midlife is a period of waning fertility. However, the occurrence of anovulatory menstrual cycles is unpredictable. Contraceptive methods also become increasingly contraindicated, both medically and physiologically. This article reviews the physiology of waning fertility and midlife contraceptive options, and discusses implications for helping women meet their contraceptive needs throughout the perimenopausal period.