Biology

• The menstrual cycle of the typical female is 28 days long. Day one is the day her period starts. In females with 28-day cycles, an egg is released from an ovary at day 14 in the process of ovulation. Between days 14 and 17, approximately, a woman is fertile. Women wishing to become pregnant that have intercourse on these days will have a good chance of conception. Avoiding intercourse during these days is known as the rhythm method of birth control.
  
  

Features

• The rhythm method typically has a success rate of about 75 percent, which is considered to be fairly low as far as birth control methods are concerned. The success of the rhythm method is highly dependent on the female knowing how long her menstrual cycle is. For instance, a woman with a menstrual cycle that is 26 days long can still use the rhythm method, but she must know when she is ovulating for it to be entirely effective.
  
  

Considerations

• Sperm cells can live in the female reproductive tract for two to three days. This makes it important to not only avoid having sexual intercourse on day 14 of the menstrual cycle, but to also avoid it for the two to three days prior to day 14. This creates approximately one week where a woman should avoid having intercourse in order to be fully protected against pregnancy.
  
  

Identification

• A woman's body makes slight changes during ovulation, and she can use these as signs if she is in tune with her body. For instance, basal body temperature increases slightly and she may notice increased cervical mucus and ovarian cramping during ovulation.
  
  

Other Options

• Because sexual intercourse should be avoided for nearly an entire week during every month if the rhythm method is used, other forms of birth control can be used during this time. Condoms, diaphragms, spermicides or a combination of any of these can effectively reduce the chance of pregnancy when used for intercourse during ovulation.