Natural FP - Disadvantages
For the natural family planning to work, both partner's cooperation is required. The method does not provide protection against sexually transmitted diseases including HIV & AIDS. It also requires a lot of time and effort to track and monitor the changes in your temperature, mucus and the days in the menstrual cycle. Other factors such as medicine and infection may also cause your basal temperature and mucus to change giving you the wrong signals. Natural family planning is less effective than other methods and about 25% of women on this method end up pregnant.
Attribution: Avallain