Basal Body Temperature Basics

In order for you to really benefit from charting your BBT, you need to know what to expect. Remember: The first two weeks of your cycle, the temperature should be low. Then, there will be a small dip in the temperature followed by a quick rise. It will stay high for about two weeks and then it will go down again and you will get your period—unless you're pregnant, of course! Start a fresh chart on the first day of your period.

So when are you most fertile? That little dip in temperature and sharp rise are the days you are ovulating. The days just prior to ovulation are the best for trying to conceive. Even though your chart won't tell you when you're ovulating until the entire cycle has been tracked, it is a great way to come to understand your cycle. "A woman then knows," says Beltsos, "that the right things are happening and all is in order."

Some BBT FAQs

Even though you know the basics of BBT now, you still may have some questions.

Do I Have to Take My Temperature Every Day?

Yes, you absolutely have to take your temperature each and every day if you are to get reliable results. If you don't, there will be blank spots in the chart, and you will be unable to determine whether or not you are actually ovulating.

So, I Just Take My Temperature and Write It Down?

While you can just write down your temperature and leave it at that, in order to best track your fertility (and not just ovulation) you should also note any symptoms you may have. Note when you have cervical mucus and what color it is. Be sure to make note of when you are having sex, exercising, experiencing spotting, or anything else relevant. This way, once it comes time to review your BBT for the past month, you won't have to question what might have caused a sudden spike in your temperature during a time when you shouldn't be ovulating.

What Happens If I Still Don't Conceive?

If you have charted your BBT faithfully for several months and attempted to conceive during your fertile window and still have not conceived, it may be time to make a visit to your doctor. There may be another issue causing your infertility that the BBT charting cannot pick up. Don't neglect to consider male factor infertility.

If I Don't See a Dip And Then a Spike in My Temperature, Am I Definitely Not Ovulating?

Not necessarily. You may have an irregular cycle or you may have exercised a lot, taken some medication, or even had sex causing your temperature to go haywire. If after a few months you still don't see the dip and spike, it may be time to consult your doctor about the possibility of underlying fertility conditions.