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Pregnancy - identifying fertile days

Fertile days are the days a woman is most likely to get pregnant.

See also: Infertility


When trying to become pregnant, many couples plan intercourse between days 11 - 14 of the woman's 28-day cycle. This is when ovulation occurs.

However, it is hard to know exactly when ovulation will happen. Doctors recommend that couples who are trying to have a baby have sex between days 7 and 20 of a woman's menstrual cycle. In order to become pregnant, having sex every other day or every third day works just as well as having sex every day.

  • Sperm can live inside a woman's body for 3 - 5 days.
  • However, a released egg only lives for 4 to 12 hours.
  • The highest pregnancy rates have been reported when the egg and sperm join together within 4 to 6 hours of ovulation.

If you have an irregular menstrual cycle, an ovulation predictor kit can help you know when you are ovulating. These kits check for LH (luteinizing hormone) in the urine. You can buy them without a prescription at most drug stores.

There are other various other methods to help detect when you are most likely to be able to conceive a baby.

Note: Some lubricants can interfere with conception. If you are trying to get pregnant, you should avoid all douches and lubricants (including saliva), except those specifically designed to not interfere with fertility (such as Pre-seed). Lubricants should never be used as a method of birth control.


Cervical fluid protects the sperm and helps it move toward the uterus and fallopian tubes. Cervical fluid changes occur when the woman's body is getting ready to release an egg. There are clear differences in how it looks and feels during the woman's monthly menstrual cycle.

  • No cervical fluid is present during the menstrual period.
  • After the period over, the vagina is dry and no cervical fluid is present.
  • Fluid then turns to a sticky/rubbery fluid.
  • The fluid becomes very wet/creamy/white which indicates FERTILE.
  • The fluid becomes slippery, stretchy, and clear like an egg white, which means VERY FERTILE.
  • After ovulation, the vagina becomes dry again (no cervical fluid) The cervical mucus may become more like thick bubble gum.

You can use your fingers to see how your cervical fluid feels.

  • Find the fluid inside the lower end of the vagina.
  • Tap your thumb and first finger together -- if the fluid stretches while you spread your thumb and finger apart, this could mean ovulation is near.


After you ovulate, your body temperature will rise and stay at a higher level for the rest of your ovulation cycle. At the end of your cycle, it falls again. The difference between the two phases is most often less than one degree.

  • You can use a special thermometer to take your temperature in the morning before you get out of bed.
  • Use a glass basal thermometer or a digital thermometer that is accurate to the tenth of a degree.
  • Keep the thermometer in your mouth for 5 minutes or until it signals you that it is done. Try not to move too much, as activity can raise your body temperature slightly.

If your temperature is between two marks, record the lower number. Try to take your temperature at the same time every day, if possible.

Create a chart and write down your temperature every day. If you look at a complete cycle, you will probably notice a point at which the temperatures become higher than in the first part of your cycle. The rise is about 0.2 degrees or more above the previous 6 days.

Temperature is a useful indicator of fertility. After checking for several cycles, you may be able to see a pattern and identify your most fertile days.


Jensen JT. Mishell DR. Family planning: contraception, sterilization, and pregnancy termination. In: Lentz GM, Lobo RA, Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, Pa: Mosby Elsevier; 2012:chap 13.

Lobo RA. Infertility: etiology, diagnostic evaluation, management, prognosis In: Lentz GM, Lobo RA, Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, Pa: Mosby Elsevier; 2012:chap 41.

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Review Date: 3/11/2014
Reviewed By: Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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