Many couples choose a natural method because of religious or personal beliefs. The penis is withdrawn from the vagina before the male ejaculates. This method has a high failure rate because sperm may enter the vagina before the penis is removed. This involves flushing the vagina with a liquid. This method is not very effective.
Many sperm continue up to the ovary and can fertilize the egg.
This means a woman avoids sex during the middle of her menstrual cycle . This method has a high failure rate. This method is not entirely reliable in preventing pregnancy. A backup method of birth control, such as a condom, should be used. Barrier methods use physical or chemical blocks to keep sperm from fertilizing the woman's egg.