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There are many ways to evaluate ovulation. The simplest of these is the basal body temperature (BBT) chart. This is an inexpensive, noninvasive, and relatively easy test. Using a specialized thermometer, the woman takes her temperature every morning before getting out of bed or doing anything, and then records it on a special chart.
If BBTs are recorded for a couple of months, they will provide the physician with important information about the cycles. BBTs will demonstrate clearly not only the length of the cycles, and their regularity, but also the approximate time of ovulation and the length of the second half of the cycle.
There are several aspects of BBTs that are important to remember:
- Don't try to interpret them yourself, especially day to day. It will drive you crazy trying to make sense of the changes. Temperature charts really only make sense when looked at in terms of the entire cycle.
- Don't use temperatures to predict ovulation. The temperature goes up after you ovulate—once the temperature goes up it is too late to have intercourse in hopes of getting pregnant. You may hear that there is a drop in the temperature at the time of ovulation and that this can be used to time intercourse. Well, sometimes there is and sometimes there isn't, but it certainly isn't reliable enough to use to time intercourse. (Ovulation predictors work much better.)
- Don't record BBTs for too long. A couple of cycles is usually enough unless the physician wants to evaluate the response to a change in medications. Infertility is difficult enough—the last thing you need is a daily reminder in the form of a thermometer in your mouth the first thing when you wake up every morning.
- If you forget a couple of days, don't worry. Just record as many days as you can.
- Record any information on the chart you think may be worthwhile.
- After a couple of months, sit down with your physician and review the charts.
There are also many brands of ovulation predictors sold over the counter. Most of these are very simple to perform, one-step tests that you do at home. All of these tests function by identifying large amounts of the hormone LH in the urine. (LH is the trigger of ovulation and rises significantly twenty-four to thirty-six hours before ovulation.) These are reliable tests and are good predictors of ovulation. They can be helpful not only for timing intercourse, but also for providing additional information when coupled with a BBT chart.
The Postcoital Test
The cervical mucus thins out just prior to ovulation and actually facilitates the transfer of the sperm to the uterus. The postcoital test (PCT ) is a good way to evaluate not only the cervical mucus, but also the interaction of the sperm and the mucus. This test must be performed right around the time of ovulation. It cannot be performed more than a couple of days before ovulation, nor after ovulation, as the cervical mucus will be too thick for this test to be meaningful.
Following intercourse, a sample of cervical mucus is gently removed from the cervix at the time of a normal pelvic exam and evaluated microscopically. The quality of the cervical mucus as well as the number of sperm present and their motility can all be checked. While it is often stated that this test must be performed within two hours of intercourse, it can actually be checked as many as 12 to 14 hours after intercourse (do not douche or take a bath, but showers are OK) as long as the physician is informed of the time. If properly timed, this test reveals a great deal about the adequacy of the cervical mucus production, the survivability of the sperm in the cervical mucus, and the interaction of the sperm and the cervical mucus.