How Effective?
Effectiveness depends on the user: Risk of pregnancy is greatest when couples have sex on the fertile days without using another method.
- As commonly used, in the first year about 25 pregnancies per 100 women using periodic abstinence. (How these women identified their fertile time is not known. Pregnancy rates for most of the specific fertility awareness methods as commonly used are not available.) This means that 75 of every 100 women relying on periodic abstinence will not become pregnant. Some newer fertility awareness methods may be easier to use and, thus, more effective (see Question 3).
- Pregnancy rates with consistent and correct use vary for different types of fertility awareness methods (see table, below).
- In general, abstaining during fertile times is more effective than using another method during fertile times.
Pregnancy Rates With Consistent and Correct Use and Abstinence on Fertile Days
| Method |
Pregnancies per 100 Women Over the First Year |
| Calendar-based methods |
| Standard Days Method |
5 |
| Calendar rhythm method |
9 |
| Symptoms-based methods |
| TwoDay Method |
4 |
| Basal body temperature (BBT) method |
1 |
| Ovulation method |
3 |
| Symptothermal method |
2 |
Return of fertility after fertility awareness methods are stopped: No delay
Protection against sexually transmitted infections (STIs): None.
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