Women tend to ovulate mid-cycle; however, it is more accurate to say that they ovulate fourteen days before menstruation. Women have been known to ovulate at any time during their cycle, including during menstruation, although this is unusual. In terms of conception, fertility depends on three factors: a healthy egg, healthy sperm, and favorable cervical mucus. A woman ovulates once a cycle. The egg lives twelve to twenty-four hours and then disintegrates if not fertilized. Under favorable cervical mucus conditions (cervical mucus nourishes and guides the sperm, which would otherwise die in about a half-hour or never reach the egg), sperm can survive as long as five days within the body.

The symptothermal method of fertility awareness is the most exact way to determine the best times for conception. This method has two parts: 1) before a woman ovulates, mucus observations are combined with predictions based on past cycle history (using a calendar calculation), and 2) to confirm ovulation, changes in basal body temperature are combined with cervical mucus observations.