Reasons for a Dip in Basal Body Temperature After Ovulation

Woman examining her basal body temperature chart

A dip in basal body temperature after ovulation may indicate a problem that can make it difficult to successfully conceive. To determine if this is a problem in your case, you will need to learn how to chart your basal body temperature throughout your cycle and accurately track changes in temperature. While this may sound intimidating, it is really quite simple and worth learning if you are trying to conceive or trying to avoid conception.

Charting Basal Body Temperature

Charting your basal body temperature, or BBT, is the easiest way to determine if you tend to have a drop in basal body temperature after ovulation. While you can keep track of this on a regular sheet of paper, it is much simpler to do if you have a BBT record form, which can be purchased or found for free online.

In order to accurately read your chart, you will need to keep records for several months. You will then begin to see a pattern that will show you when you ovulate and when you don't. You will also be able to see any irregularities in your cycle that may be a problem if you are trying to conceive.

How to Do It

First, you will need to purchase a basal body thermometer. This type of thermometer is more accurate that a regular thermometer because it measures your temperature to a tenth of a degree. You will need to be this precise while charting your BBT. Keep this thermometer next to your bed along with a pen and your BBT chart for the month.Each morning when you wake, before doing anything else, take your temperature. You can do this orally, vaginally or rectally, but whichever way you choose it must be the same way every time.

Mark your chart with a dot to indicate your temperature that day. After several days, you can begin to connect the dots and see how your temperature fluctuates from day to day. These fluctuations will be small until you are ready to ovulate. Most women see a slight drop in their BBT just before ovulation followed by a spike when they ovulate. If you are trying to conceive, this drop indicates the best time to have intercourse.

A rise of about .4 degrees or higher sustained for three or more days indicates that you have ovulated. This sounds like a tiny temperature change, but on your BBT chart it will look huge. See the image about for an example.

A Dip in Basal Body Temperature After Ovulation

Typically, after you ovulate your BBT will stay elevated for about 12 days. If you notice a drop in basal body temperature after ovulation, this may indicate a problem. You may have a short luteal phase or a luteal phase defect. This may cause problems if you are trying to have a baby.

Luteal Phase

What is a luteal phase? The luteal phase is the second phase of your cycle, which is triggered by the release of the egg from the follicle. The follicle is now called the corpus luteum and this is what produces progesterone.

Progesterone is necessary to cause the lining of your uterus to thicken, allowing a fertile egg to attach itself and form an embryo. If conception does not take place, the corpus luteum dies and is shed from your uterus when you have your period.

Short Luteal Phase

Normally, the luteal phase lasts from 12 to 14 days. A luteal phase that is shorter will not allow for enough progesterone to be produced in order to sustain a pregnancy. If your BBT chart shows a drop too soon after ovulation, you should consider also using an ovulation predictor kit along with your chart so you can show the results to your doctor. A luteal phase that is 10 days or less indicates that you may not be able to successfully conceive.


Fortunately, a short luteal phase is not uncommon and can usually be treated successfully. Your doctor may test your blood progesterone level or schedule an endometrial biopsy in order to make an accurate diagnosis.

An endometrial biopsy isn't as scary as it sounds. Your doctor will scrape a small sample of your uterine lining and send it to a lab for evaluation. If the cells analyzed are not consistent with how they should look on that day of your cycle, then they will be categorized as out-of-phase. Now treatment can begin.

Your doctor may chose to give you progesterone supplements or fertility drugs such as Clomid. Feel free to discuss any suggestions for treatment with your doctor so you feel comfortable and understand what is happening. Most times, these treatments are very successful in helping women conceive the baby they have been longing for.

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Reasons for a Dip in Basal Body Temperature After Ovulation