Measure the Basal Temperature


What does the basal body temperature got to do with ovulation?

This method is a part of the popular Fertility Awareness Method. The basal body temperature is the temperature you body has when resting, measured immediately after awakening and before any physical activity has been undertaken. In women, ovulation causes an increase of one-half to one degree Fahrenheit (one-quarter to one-half degree Celsius) in basal body temperature (BBT); monitoring of BBTs is one way of estimating the day of ovulation. This rise in temperature usually occur the day after ovulation. The tendency of a woman to have lower temperatures before ovulation, and higher temperatures afterwards, is known as a biphasic pattern. Charting of this pattern may be used as a component of fertility awareness.

Unfortunatly, since the temperature rise AFTER the ovulation has occured, it is only a useful method to determine that ovulation did occur and to map your cycle.

Below is a diagram of chances of conception on given days relative to the rise in temperature:

diagram showing the chances of conception

Photo: www.fertilityuk.org

It is also useful for finding out if the Luteal phase is long enough for the egg to attach and when you can expect you period.

 

How to measure the temperature

  • Use a termomether with two decimals. You can buy Digital Basal Thermometers online at amazon.com
  • Ear termomethers are too inacceurate. It is also inaccurate to measure under the arms.
  • The best is to use a basal thermomether, they can be hard to find in shops but can be ordered on the net.
  • Measure in the mouth. Put the thermomether well and truly under the toung
  • If your temperatures vary a lot from measuring in the mouth, you should switch to vaginal or anal measurement. Be consisten and use the same place of measuring throughout the whole cycle. Any swap must happen at the start of a new cycle.
  • Measure on approxomately the same time of day each time. If you get up earlier or later, the temperature will be higher og lower.
  • If you do not want to get up early on the weekends, just put the alarm on, take the temperature and go back to sleep. most digital thermometers registers the last measured temperature so you can get it later.
  • You have to have a minimum of three hours continous sleep
  • Have a sheet of paper and something to draw a curve on. Note the temperature daily and draw lines between the temperatures.
  • Note unusual events like little sleep or too much alcohol on the curve. This may affect the curve and must be taken into account during the evaluation.
  • It can be useful to note intercourse, PMS, ovulation pains and other cycle related hassles as well. It can be useful when mapping your fertility.
  • Temperatures that are disturbed because of too early or too late measurement can be adjusted. The rule here is to adust max 0.05°C for every half hour. Adjust up if you measure too early and don if you measure too late. Don’t bother adjusting if you are only half an hour late og early.

 

How to analyse the temperature curve

  • The temperature will probably swing a little, so you must not get hung up on a each single temperature, but look at the curve as a whole.
  • Temperatures differing from the others because of illness, alcohol etc. must be ignored.
  • A usual temperature curve (biphase curve) will have two levels. A low level before ovulation and a high level after ovulation.
  • Curves where the temperature jumps up and down or stay pretty constant (monophase curve), are a sign of a cycle without ovulation. This is normal some times, but if this happend often you should see a gynechologist.
  • A curve can also have three levels - a low one before ovulation, a high one after ovulation, and an even higher one a week after ovulation. These curves are called triphase curves, and are often a sign of pregnancy. See example of triphase curve.However, you can have a triphase curve without being pregnant and you can be pregnant without having a triphase curve.
  • In order to separate between the low temperature levels before ovulation and the high temperature levels after ovulation, it is a good idea to draw up a so called “coverline”. You can find it by drawing a horizontal line 0,05°C above the highest of the last 6 low temperatures before the temperature rose.
  • Curves where the luteal phase lasts for 18 days or longer this often means pregnancy.
  • Curves wihere the luteal phase is 10 days or less tells us that the egg POSSIBLY lacks time to digg down and notify the body that a pregnancy is happening. You should see a gynechologist if you luteal phase is too long.

Temperature dipper

  • Some people experience a dipp in the temperature right before ovulation. The might be a sign of an ovulation about to occur. However, not everyone experience these dipps. Even if you have exdperienced it before dosn’t mean if will happen next time, so don’t look for the temperature dipp to predict the ovulation - you can get tricked.
  • Some experience a dipp in the temperature about one week after ovulation, many call this an “attachment dipp”. The experts cannot agree about whether it should have this name, because the dipp com at the same time as a slight upswing in the levels of estrogen (called the estrogen wave, se the hormone curve). I agree with those who doubt the phenomena because it is the estrogen that keeps the temperature low during before the ovulation, so it is likely that this is the cause after ovulation as well.


Inspiration sources: “Taking charge of your fertility”
by Toni Weschler