How It Is Done continued...
Record the dates of your menstrual periods for 6 to 8 months. See if your menstrual cycle is regular and how many days it is. If your cycle is regular and about 28 days long, you are most likely to ovulate 14 to 15 days after menstrual bleeding begins.
To find the first day that you are likely to be fertile, take 18 away (subtract) from the number of days in your shortest menstrual cycle. Your first fertile day should be that many days after your menstrual bleeding begins. For example, if your shortest menstrual cycle is 26 days long, you would subtract 18 from 26 to get 8; your first fertile day would then be the 8th day after menstrual bleeding begins.
To find the last day that you are likely to be fertile, subtract 11 from the number of days in your longest menstrual cycle. Your last fertile day should be that many days after your menstrual bleeding begins. For example, if your longest menstrual cycle lasts 31 days, you would subtract 11 from 31 to get 20; your last fertile day would then be the 20th day after menstrual bleeding begins.
Sperm can live in your vagina 3 to 5 days after sex.
- If you want to become pregnant, have sex every day or every other day from your first fertile day to your last fertile day.
- If you do not want to become pregnant, do not have sex or be sure to use another method of birth control for 1 week before your first fertile day. In the example above, your fertile period is from day 8 to day 20, so protect yourself from becoming pregnant for these 12 days of your cycle.
The calendar method of birth control is not the best choice for women who have short, long, or irregular menstrual cycles. For this reason, the calendar method alone is never recommended for birth control. It must be used in combination with other birth control methods.
Standard days method (SDM)
On the first day of your period, move the ring to the red bead (day 1) on the CycleBeads. Count each day as one bead. On days 1 to 7, you can have unprotected sex. On days 8 to 19, do not have sex or be sure to use another method of birth control to avoid pregnancy. From day 20 to the end of your cycle, you can have unprotected sex. All brown beads are days when you are not likely to become pregnant. All white beads are days you are likely to become pregnant. The dark brown bead marks day 26 and the last brown bead before the red bead is day 32. The SDM works best for women who have cycles between 26 and 32 days long.
Basal body temperature (BBT) method