Fertile cervical mucus, which occurs just before ovulation, typically lasts between three and four days, according to the Mayo Clinic. Women that are trying to conceive can monitor their cervical mucus patterns to identify their most fertile days each month and increase their chances of conception.
Ovulation usually occurs mid-way through a woman's menstrual cycle. A woman is most likely to conceive if she has sexual intercourse in the few days leading up to ovulation. The Mayo Clinic explains that before a woman ovulates, she usually notices changes in her cervical secretions. At her most fertile time, a woman's secretions are abundant, clear and wet. This produces an environment that encourages sperm to travel through the cervix, uterus and fallopian tubes to reach the egg, thereby increasing the likelihood of conception.