Basal Body Temperature Method
Worldwide, the basal body temperature method is the oldest and most widely practiced of the fertility awareness methods. Every woman is different, so your temperature pattern may vary from the example below. The woman should assume that body temperature will increase noticeably (0.4-0.8 Fahrenheit) at ovulation. Most women ovulate (release an egg from the ovary) at about day 14 of their menstrual cycle, plus or minus 2 days. The egg is viable for about one day, and sperm usually live for 2-3 days (occasionally up to 6-7 days).
Make a calendar like the one below, but without the example line. Keep a daily calendar record of the temperature using a regular thermometer (or digital) under your tongue for 3 minutes. Take your temperature after you wake up in the morning but before you get out of bed. On the same record, chart your menstrual cycle, beginning with day 1 as the first day each month that you begin your period. If possible, chart your temperature pattern for a few months before relying on it.
WHAT ARE THE ADVANTAGES?
•It's absolutely free!
•No side effects
•There are no side effects or complications from hormones.
•This method may actually be used to help couples achieve pregnancy.
WHAT ARE THE DISADVANTAGES?
•This method is not a good choice if your periods don’t come at a regular time each month, your temperature pattern is different each month, you just stopped birth control pills, you just started having your periods, you are close to menopause, you can’t keep a calendar chart, or you don’t like going without sex for a least two weeks.
•It takes at least 6 months of recording cycles to learn how to use natural family planning. During this time, you must abstain from sex or use a barrier method.
•This method is often unreliable during times of stress or illness because cycles may be irregular and/or basal body temperature fluctuations may occur.