How to use ovulation charting and basal body temperature tracking to optimize your fertility

photo of ovulation calendar and thermometer

When you are ready to get pregnant, it can be hard to wait for that second blue line to appear on a home pregnancy test. But be patient.

About 80% of couples get pregnant within the first six months after trying and 85% of couples continue to get pregnant within the next 12 months, says Alyssa Lawler, APRN-CNM, nurse midwife.

Fertility-based planning

To optimize fertility, some couples have resorted to fertility-based planning to optimize their fertility. The fertility-based planning method involves identifying the fertile days of the menstrual cycle using a combination of cycle length and physical signs of ovulation, including changes in basal body temperature and vaginal secretions.

“Often women are not aware of their menstrual cycles and the important role they play in increasing the chances of them getting pregnant,” says Lawler. “The fertility-based planning method can be very effective in identifying the days when you are fertile and most likely to get pregnant.”

The fertile window

The average menstrual cycle is 28 days long. Cycles that are between 25 and 35 days usually release a mature egg that can be fertilized. In every menstrual cycle, you have a six-day window in which you can get pregnant, Lawler explains. It consists of five days before ovulation and extends to the 24 hours after the day of ovulation. Identifying the fertile period and timing of intercourse during this six-day interval maximizes the likelihood of fertilization. Fertility is based on the viability of the egg and sperm. Your eggs are released during ovulation and usually remain viable for about 12 to 24 hours after they are released, while sperm have a viability of three to five days in cervical mucus and the upper genital tract. Therefore, find the highest probability of getting pregnant with unprotected intercourse two days before ovulation, Lawler says.

Track your temperature

Your basal body temperature rises by about 0.5 degrees Fahrenheit one or two days after ovulation. To identify this post-ovulatory window, you need to monitor your basal body temperature every morning before getting up and starting your day with a specific thermometer that can track temperature rises by a tenth of a degree.

Am I ovulating?

“It is important to identify this window, but changes in basal body temperature occur one to two days after ovulation occurs, at which time the fertile period is over,” Lawler explains. “This is a retrospective event and therefore the identification of temperature changes alone is too late to be useful for the timing of sexual intercourse to conceive. However, detecting changes in basal body temperature can help identify whether you are ovulating,” “because some women have cycles in which they should not release an ovum. If you do not ovulate every month or if you have irregular menstrual cycles, you should be seen and evaluated by an OB-GYN specialist.”

Ovulatory disorders can be identified in 18% to 25% of couples presenting with infertility, Lawler says. Most of these women have irregular periods, which occur every 35 days to six months. When this happens, even though ovulation can sometimes occur, spontaneous fertilization is unlikely.

Follow cervical secretions

To boost the effectiveness of this method, you can also combine basal body temperature detection with recording your cervical secretions, Lawler says. It involves monitoring your cervical secretions several times a day. Just before ovulation, you will see an increase in vaginal mucus that is clear, stretchy and smooth, making sperm move more easily.

Periods in which you are least fertile are 24 hours after ovulation until the end of your period each month.

Challenges for fertility-based planning

While the fertility-based planning method can increase the chances of pregnancy for women who can identify their fertile period, it also has several disadvantages, Lawler says. These include:

  • There is not very easily accessible information on how to use the method
  • It can take a considerable amount of time to learn to use the method effectively
  • It is labor intensive for both the patient and the provider instructing you on how to use the method
  • You must be highly committed to using the method and have a supportive partner
  • The method is not effective if you have irregular menstrual cycles, for women diagnosed with polycystic ovary syndrome (PCOS), recent menagerie or perimenopause
  • After pregnancy, many women will experience irregular menstrual cycles. To be effective, you will need approximately four months of regular periods before using the method.

Prevention of pregnancy

The fertility-based planning method can also be used for pregnancy prevention, although it is not widely used due to the dedication and learning curve required to use the method, Lawler notes. “When followed perfectly, only 0.4% to 0.5% of women will become pregnant in the first year,” she says. “With typical use, however, about 25% of women become unintentionally pregnant within the first year of use.”

If you have not become pregnant after six months of trying, you should consider seeing your doctor to help identify any other potential problems, Lawler says. If no one is identified, your doctor may recommend using the fertility-based planning method to optimize fertilization. “The good news is that an additional 50% of couples will get pregnant spontaneously over the next 36 months,” Lawler says.

Do you need a fertility consultation?
To schedule an appointment with one of our OB-GYNs or fertility specialists, call 800.922.0000.

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