Fertility Awareness - The Menstrual Cycle

Being aware of your menstrual cycle and the changes in your body that happen during this time can be key to helping you plan a pregnancy. However, knowing the signs of ovulation does not work well as a birth control method. During the menstrual cycle (a total average of 28 days), there are two parts: before ovulation and after ovulation.

Day 1 starts with the first day of your period. Usually by Day 7, a woman's eggs start to prepare to be fertilized by sperm. Between Day 7 and 11, the lining of the uterus (womb) starts to thicken, waiting for a fertilized egg (embryo) to implant there.

Around Day 14 (in a 28-day cycle), hormones cause the egg that is most ripe to be released, a process called ovulation. The egg travels down the fallopian tube towards the uterus. If a sperm unites with the egg here, the fertilized egg (embryo) will attach to the lining of the uterus, and pregnancy occurs.

If the egg is not fertilized, it will break apart. Around Day 25 (if no pregnancy has occurred), when hormone levels drop, it will be shed from the body with the lining of the uterus as a menstrual period.

The first half of the menstrual cycle is different in every woman, and even can be different from month-to-month in the same woman, varying from 13 to 20 days long. This is the most important part of the cycle to learn about, since this is when ovulation and pregnancy can occur. After ovulation, every woman (unless she has a health problem that affects her periods) will have a period within 14 to 16 days (if pregnancy has not occurred).

Knowing when you re most fertile will help you plan a pregnancy. (Not useful as a birth control method). There are three ways you can keep track of your fertile times. They are: basal body temperature method, the calendar method and the cervical mucus method. See our pages on these topics for more information.

This information is supplied by The National Women s Health Information Center. The National Women s Health Information Center is Sponsored by the Office on Women s Health in the U.S. Department of Health and Human Services.