The menstrual cycle is the monthly series of changes in the female reproductive system that make pregnancy possible. The cycle is divided into four phases: the menstrual phase, the follicular phase, the ovulation phase, and the luteal phase. The ovulation phase is the time when an egg is released from one of the ovaries. This usually happens 14 days before the start of the next menstrual period. The days leading up to ovulation are the most fertile days of the menstrual cycle, as this is when an egg is most likely to be fertilized by sperm.
Knowing when you are most fertile can be helpful if you are trying to conceive or avoid pregnancy. There are a number of ways to track your ovulation, including using ovulation predictor kits, charting your basal body temperature, or using a fertility monitor.