How does it work?
There are minute changes in your body temperature that correlate with your fertility. After keeping track of your basal body temperature for several months you should be able to estimate when you are fertile and when you are not. If you abstain from sex while you are fertile you can reduce your risk of getting pregnant.
How to record your temperature
- You must take your temperature every morning before you do anything (including talking)!
- It is important to take your temperature the same way every day. For instance, if you start taking your temperature orally, you should always take it orally.
- Record your temperature daily on a BBT chart. You can get one of these charts from your doctor, local family planning clinic.
- If possible, take your temperature with a BBT thermometer. These thermometers are specially made to measure tiny changes in your body temperature that may be hard to read on other kinds of thermometers.
- Since learning to use this method can be tricky, you should call your local clinic to see if they offer any classes.
You are fertile when…
You can assume that your safe days start when your temperature has risen anywhere from 0.2°C to 0.5°C and stayed that way for at least three days. Your temperature will usually stay elevated until right before your next period.
In order to prevent pregnancy you should abstain from having intercourse during your fertile periods. If you choose to have intercourse, it is a smart idea to use a backup method of birth control such as condoms. If you really want to be safe you can use both withdrawal and condoms.
Advantages
- This method is inexpensive! In fact, the only cost involved with this method is the cost of the thermometer and graph paper. BBT thermometers are a little more expensive than regular thermometers.
- Using this method gives you an opportunity to get to know your body better.
- This method is great if you are not comfortable using other methods of birth control for personal, religious, or medical reasons.
- Many people like that this method does not involve taking hormones or using chemicals.
Disadvantages
- You have to be very disciplined. Using BBT as a method of birth control requires that you take your temperature at the same time, the same way, EVERY day. This method can only be trusted when it is practiced perfectly.
- The BBT Method requires that you abstain from having sex during your fertile periods, which for some women can be several weeks out of each menstrual cycle.
- It is not as effective as many other methods of birth control.
- It can be hard to read changes in temperature on a regular thermometer.
- The BBT method does not offer any protection against sexually transmitted diseases.
Cost
This method is practically free! The only things you need to pay for is a thermometer, charts to record your cycles on, and any fees for taking classes training you in this method.
Effectiveness
Perfect users have a failure rate of 2%, whereas typical users have a failure rate of 20%.
© - Reproduced with permission of SexInfo, University of California at Santa Barbara, 2007.