Natural Family Planning: The Standard Days Method ®
The Standard Days Method (SDM) is a new method of Natural Family Planning (NFP) developed by the Institute for Reproductive Health at Georgetown University. SDM is 95% effective when used correctly. 5 out of 100 women practicing this method correctly for one year will get pregnant. The effectiveness of any method of NFP varies from couple to couple. All NFP methods are significantly less effective for couples who do not follow the method closely.
SDM works for women with menstrual cycles from 26 to 32 days long. To use the method, couples abstain from sexual intercourse on days 8 through 19 of the woman's menstrual cycle or uses condoms and spermicide. If a woman has more than one cycle per year that is shorter than 26 days, or longer than 32 days, the method effectiveness decreases significantly and a different method of NFP should be used.
Using the Standard Days Method:
1. On any ordinary calendar, mark the day when your period first begins as Day 1 and circle it.
2. Then mark the same day of the week, one week later, as Day 8 and circle it.
3. Count forward from Day 8 to Day 19 and circle it.
4. Draw a solid line through days 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 19.
For these twelve days (days 8 through 19), abstain from all sexual intercourse, if you wish to avoid conception.
Below is an example of how to mark your calendar.
5. When your next period begins, mark that day as Day 1 of the next cycle.
6. Then go back to the previous cycle on the calendar and count the total number of days in the previous cycle. Put a square around the total number of days for each cycle. So if a cycle was 30 days long, the last day will be marked 30.
Keep these calendar pages, so that you have a record of how long each cycle was. Only one cycle per year can be less than 26 days, or more than 32 days.
If more than one cycle per year was shorter than 26 days or longer than 32 days, use a different method of Natural Family Planning.
Why the Standard Days Method works
Researchers at the Institute for Reproductive Health at Georgetown University discovered that ovulation most often occurs about the midpoint of a woman's menstrual cycle.
30.1% of cycles had ovulation at the midpoint of the cycle. In approximately 89% of cycles, ovulation occurs within plus or minus 3 days of the midpoint day.
The chance of conception from intercourse on the day of ovulation is 8 to 10%.
But SDM also takes into account the chance of conception from sexual intercourse in the days before and after ovulation. The ovum remains viable for only 12 to 24 hours after ovulation, so conception can occur from sexual intercourse no later than one day after ovulation. The sperm remain viable for 5 to 6 days after intercourse, so conception can occur from sexual intercourse up to 5 or 6 days prior to ovulation. However, the probability of conception from intercourse even 5 days before ovulation is only about 5%.
The greatest chance of conception occurs one and two days before ovulation.
Taking into account these percentages, researchers determined a fertile window within the menstrual cycle (see the fertile window chart below) from day 8 through day 19.
They tested their method in a study of 478 women for a total of over 4,000 menstrual cycles. The study demonstrated the method to be over 95% effective with correct use. The method was 88% effective in typical usage (some couples did not always abstain during the entire fertile time).
Since the study, SDM has been used by many women around the world. SDM has proven to be an effective, safe, easy-to-learn method of NFP.
Like always, I would love to know if anyone has used this method, has any additional research or real life experiences?