Fact 1: Ovulation occurs on about the 14th day of menstruation.
Ovulation refers to the release of an egg from the ovary. In a typical menstrual cycle, ovulation usually occurs around the 14th day. This is considered the most fertile period for a woman, as the released egg can be fertilized by sperm.

Fact 2: Ovum remains alive for about 1-2 days.
Once an egg is released during ovulation, it has a lifespan of about 1-2 days. If it is not fertilized during this time, it will disintegrate and be expelled during the next menstrual cycle. This means that the window of opportunity for fertilization is relatively short.

Fact 3: Sperms survive for about 3 days.
Sperm cells, on the other hand, have a longer lifespan compared to the ovum. Once ejaculated into the female reproductive system, sperm can survive for up to 3 days. This means that if sexual intercourse occurs a few days before ovulation, the sperm can still be present and potentially fertilize the released egg when it becomes available.

Method of Periodic Abstinence:
The method of periodic abstinence, also known as the fertility awareness-based method or natural family planning, is a contraceptive method that relies on tracking a woman's menstrual cycle to determine the most fertile and infertile periods. This method is based on the aforementioned facts about ovulation, the lifespan of the ovum, and the survival of sperm.

During the fertile period, when ovulation is likely to occur, couples practicing periodic abstinence can choose to abstain from sexual intercourse or use alternative methods of contraception to avoid pregnancy. On the other hand, during the infertile period, when the egg has already disintegrated or is not yet released, couples can engage in sexual intercourse without the risk of pregnancy.

By understanding and tracking the menstrual cycle, couples can identify the fertile period and make informed decisions about when to engage in sexual activity. This method requires consistent and accurate monitoring of the menstrual cycle, including tracking basal body temperature, cervical mucus changes, and other signs of ovulation.

Conclusion:
The method of periodic abstinence is based on the facts that ovulation occurs around the 14th day of menstruation, the ovum remains alive for about 1-2 days, and sperm can survive for about 3 days. By avoiding sexual intercourse during the fertile period, couples can effectively prevent pregnancy. However, it is important to note that this method is not 100% reliable and requires careful monitoring and understanding of the menstrual cycle.