Female infertility has many possible causes. More than one problem contributes to infertility in 25% of couples.1
Problems with the menstrual cycle, the process that prepares the female body for pregnancy, can lead to infertility.
The Menstrual Cycle
The female body prepares for pregnancy through the menstrual cycle. One cycle lasts about 28 days, but it can range from 21 to 35 days. The menstrual cycle and conception are described below.
Day 1
The first day of bleeding is considered the first day of the menstrual cycle. After bleeding ends, usually around day 5, levels of the hormone estrogen begin to rise. The rise in estrogen causes the lining of the uterus to grow as it prepares to hold a fertilized egg. At the same time, the changes in hormone levels cause an egg to start to mature in one of the ovaries.
Ovulation
Around day 12, the egg leaves the ovary in a process called ovulation (pronounced ov-yu-LAY-shuhn). Ovulation can occur anywhere between 10 and 21 days after the first day of a woman's menstrual cycle. A woman can tell when she has begun ovulating using several methods, including at-home tests that measure hormone levels in the urine and by keeping track of her body temperature.
Fertilization
After ovulation, the egg moves down the fallopian tube. The sperm can fertilize the egg at this point. Fertilization of the egg is also called conception (pronounced kuhn-SEP-shuhn). After the sperm is ejaculated into the vagina, it moves into the cervix and through the uterus into the fallopian tube. Sperm can live up to 5 days in a woman's body. If fertilization occurs, the newly formed embryo travels back through the fallopian tubes into the uterus, where it implants in the wall of the uterus. If fertilization does not occur, the egg breaks apart, and the uterine wall is lost in the form of menstrual bleeding.
Implantation
The embryo must successfully implant in the thickened wall of the uterus for the pregnancy to continue. The embryo first attaches to the wall of the uterus (usually 5 or 6 days after ovulation) and then it becomes more firmly implanted between 6 and 12 days after ovulation. Implantation causes a release of hCG—a hormone that signals the body to change to support the pregnancy. This hormone is what a pregnancy test detects.
Problems at any of the stages of this cycle can lead to difficulty getting pregnant or to infertility.
Other physical factors can lead to infertility as well. Links to descriptions of different issues that affect fertility are provided below.
In some cases, health care providers cannot find a cause for infertility. In these instances, it is called unexplained infertility.
- American Society for Reproductive Medicine. (2012). Quick facts about infertility. Retrieved June 11, 2012, from http://www.asrm.org/detail.aspx?id=2322 [top]