Basal body temperature birth control method
By Mayo Clinic staffThe basal body temperature (BBT) is your body temperature at the time you wake up each day. By measuring this temperature each day and noting the day that it changes, a woman can determine when she's least and most likely to ovulate and conceive.
Effectiveness rate. The typical effectiveness rate among users of the BBT method is 80 percent, so 20 out of 100 women practicing this method for one year will get pregnant. The reliability of this method can be disrupted by:
- Illness
- Emotional distress
- Interrupted sleep cycles
- Smoking tobacco or drinking alcohol
- Using an electric blanket
Side effects and health risks. The major downside associated with using BBT as a means of natural family planning is the requirement for prolonged abstinence or use of barrier methods. Also, this method of birth control doesn't protect against STDs.
How to use the basal body temperature method. Before relying on this method, you have to familiarize yourself with your cycle by charting your BBT for three months. During that time — and for as long as you continue to use the BBT method — you take your temperature with a special BBT thermometer every morning before getting out of bed. For the method to work, you need to predict when you'll ovulate, not just to realize when you have ovulated. To do that, keep a log of each day's BBT, and watch for it to rise slightly (less than one degree) at some point between menstrual periods. This BBT increase means you have ovulated in the past 24 hours.
It's necessary to abstain from intercourse or use a barrier contraceptive every time you have sex during the three months of BBT charting. Then, when you begin to rely on the BBT method, you should either abstain from intercourse or use a barrier method on the days when conception may occur. Because sperm can live for three days in your reproductive tract, the "unsafe" interval has to include at least three days before and three days after ovulation. In other words, unprotected intercourse is off limits from your menstrual period until the night of the third day after your temperature rises, every month.
Cost and availability. Basal body temperature thermometers cost around $10. Classes that teach this technique may charge fees, which vary from region to region.
