A woman releases her egg every month and it stays 24 hrs. If there is no fertilization that will happen it will just be absorbed and menstruation occurs. However, a woman can get pregnant 3 days before her egg releases because the lifespan of the sperm is 3 days so even if the egg is just being released while the sperm is alive, fertilization occurs. In a completely fertile couple, there is a 25% chance of conception each month of unprotected sex. It takes on average about 5 months to fall pregnant. A woman’s fertility starts to decrease rapidly in her late 30s and early 40s, because of the aging of the ovary. A woman has to be under 45 for IVF, unless she will be using donor eggs. Using donor eggs, the age limit is 50. About 5% of women will fall pregnant after stopping infertility treatment.