A woman's reproductive system includes the uterus, the ovaries, and the fallopian tubes. In a healthy pregnancy, the fertilized egg implants on the uterine wall. The growing fetus develops, nourished by the placenta, for about 40 weeks until the fetus is ready for delivery. When a fertilized egg does not make it all the way to the uterus and stays in the fallopian tube (or rarely in the ovary or in the abdominal cavity), an ectopic (out-of-place) pregnancy exists. The abnormally placed cells of an ectopic pregnancy cannot become normally placed inside the uterus or develop into a normal pregnancy.