Pregnancy - identifying fertile days

• Alternative Names

  Basal body temperature

• Information

  When trying to conceive a baby, many couples plan intercourse around days 11 - 14 of the woman's 28-day cycle. However, it is often difficult to know exactly when ovulation is going to occur. Doctors recommend that couples who are trying to have a baby have intercourse between days 7 and 20 of a woman's menstrual cycle. Studies have shown that having intercourse every other day or every third day works just as well as having intercourse every day in order to become pregnant.

  Remember that the sperm can live inside a woman’s body for 3-5 days. However, a released egg only lives for 12-24 hours, so don’t wait until you think ovulation has occurred to have intercourse.

  

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  Ovulation

  If you have an irregular menstrual cycle and are no sure when or if you are ovulating, ovulation predictor kit can help. These kits, which can be bought at most drug stores, check for LH (luteinizing hormone) in the urine.

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

  Evaluating Your Cervical Fluid

  Cervical fluid protects the sperm and helps it move through the cervix toward the uterus and fallopian tubes. Cervical fluid changes in preparation for ovulation. You will notice clear differences in how it looks and feels over the course of the cycle.

  • Menstrual period occurring (no cervical fluid is present)
  • Vagina is dry (no cervical fluid is present)
  • Sticky/rubbery fluid
  • Wet/creamy/white fluid -- FERTILE
  • Slippery/stretchy/clear "egg white" fluid -- VERY FERTILE
  • Dry (no cervical fluid)

  The cervical fluid will be slippery and stretchy on your most fertile days. You can use your fingers to check the consistency of your cervical fluid. Find the fluid inside the lower end of the vagina. Tap your thumb and first finger together -- if the material stretches while you spread your thumb and finger apart, this could mean ovulation is near.

  Taking Your Basal Body Temperature

  After you ovulate, your body temperature will rise and stay at a higher-than-normal level for the rest of your ovulation cycle. At the end of your cycle, it falls again.

  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 so that you can get accuracy 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 everyday. If you look at a complete cycle, you will probably notice a point at which the temperatures become higher than they were in the first part of your cycle. More specifically, the rise is when your temperature increases 0.2 degrees above the previous 6 days.

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

• References

  Mishell DR. Family planning: contraception, sterilization, and pregnancy termination. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 14.

  Lobo RA. Infertility: etiology, diagnostic evaluation, management, prognosis. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 41.

Review Date: 12/31/2008

Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.