Periodic abstinence, often referred to as fertility awareness, natural family planning, or the rhythm method, involves avoiding sexual intercourse during the days in a woman's menstrual cycle when pregnancy is possible. Alternatively, a barrier method like a condom or diaphragm might be used on those days. Given that sperm can survive in the female reproductive tract for up to seven days and an egg is viable for around 24 hours, a woman has a significant fertile window—from seven days before ovulation to three days after. Estimating a woman's fertile period typically relies on tracking her menstrual cycle, observing changes in cervical mucus, or monitoring shifts in body temperature. However, this method of birth control carries a high risk of failure, potentially leading to pregnancy.