When do natural methods of family planning not work well?The mucus and counting days methods do not work if:
- you have little control over when you will have sex. During fertile times, your partner must be willing to wait and not have sex or to use condoms or some other barrier method.
- your fertility signs change from month to month. You will not be able to know when you are fertile.
- you have just had a baby or miscarriage. It is hard to know when you are fertile at these times.