Fertility Awareness Methods

Sexual Health Centre
Birth Control

The Calendar Method

Because ovulation usually occurs about 14 days before the start of your next period, keeping track of when you have your period can help you calculate when you are most likely to get pregnant. This is called the calendar or rhythm method. The calendar method is unreliable for women with irregular cycles. On its own, it is the least reliable fertility awareness method and should be combined with other methods.

To calculate your 'unsafe time'

1. Keep track of the first day of your menstrual cycle for eight months to a year The time between the start of each new period is the length of your menstrual cycle for that month.
2. Subtract 18 from the length of your shortest cycle For example, if your shortest cycle was 26 days, the first 'unsafe day' of your period would be (26-18 = 8) eight days after your period starts.
3. Subtract 11 from the length of your longest cycle For example, if your longest cycle was 30 days, the last 'unsafe day' of your period would be (30-11 = 19) 19 days after your period starts.

If you are using the calendar method, you should not have unprotected intercourse between these two dates.

Basal Body Temperature

A basal thermometer allows a woman to take her temperature very accurately.

Monitoring your temperature with a sensitive thermometer can help you determine when you have ovulated. You should take your temperature first thing in the morning, before you get up and start moving around. Basal thermometers show increments of 1/10 of a degree. A woman's temperature is usually lowest at the time of ovulation, and rises rapidly following ovulation. If you monitor your temperature in this way for at least three months, you can consult with someone experienced in reading basal body temperature charts to predict your ovulation.

Billings (Mucus) Method

The mucus produced by a woman's cervix changes during the 'unsafe' days around ovulation. To allow easy movement for sperm, the mucus becomes clear and slippery and can be stretched between your fingers. On safe days, there is less mucus and it is tacky and thicker. Detailed monitoring of the mucus can help predict 'unsafe' days.

The Sympto-thermal Method combines all three of these methods. It is the most effective fertility awareness method for preventing pregnancy. Not only does a woman chart her menstrual periods but she also makes daily records of her temperature and cervical mucus. Using all three methods gives a woman a more accurate prediction of when she is ovulating because the signs of ovulation using one method prompt a woman to watch for the signs of ovulation using another method. Combining the methods usually helps narrow down a shorter 'unsafe' period.

Lactation amenorrhea

This is the medical term for the period of time after giving birth when you are breast-feeding and your period has not begun. Having sex during this time is sometimes considered a fertility awareness method. Having sex during this time may be 'safe' if:

• you gave birth in the last six months
• your period has not returned
• your baby is breast-feeding
• this is the only way your baby is eating and you are not going more than 6 hours between feedings

If all of these things are true, then during the first six months following birth this method is 98 percent effective. Using a breast pump does not have the same effect as breast feeding

Ovulation Predictor Kits

These kits test a woman's urine. They measure hormone levels and indicate when ovulation is about to occur. These methods only turn positive 12 to 48 hours before ovulation; they do not indicate the start of your unsafe time. They can however be used to help chart your ovulation pattern. They are also helpful for women who want to identify the best times to try and get pregnant.