Timing Ovulation

The general rule of thumb is that most women are fertile 14 days before the start of their period. Therefore, if you start your period on the first of the month and have regular, 28-day cycles, you could expect to ovulate on the 14th day of the month. Once ovulation begins with the release of the egg into the fallopian tubes, it can live for 12-24 hours.

However, unless you have received training in natural family planning from a professional and follow all instructions to the letter, this is an extremely risky way to avoid pregnancy. The only way to avoid pregnancy 100% is to abstain from sex completely, but the next best way is to protect yourself at all times using condoms and spermicide.