The "fertility awareness" contraceptive method - timing unprotected sex to coincide with less fertile portions of a menstrual cycle - is an enduring means of avoiding pregnancy, although far from effective. Now, a Swedish startup claims it has created an app to help men and women "perfect" the process, greatly increasing its preventative efficacy. While reliable data on its modern usage is unforthcoming, it's safe to say women counting the days in between periods and avoiding sex when they're most fertile is a fairly well-known family planning method. Ova (female eggs) only live for about a day, meaning if someone has sex after one expires and before another is created, they will not get pregnant. However, if someone has sex before they ovulate, they can get pregnant, as sperm can stay alive in a uterus for around a week.

Read more at sputniknews.com