Efficacy of natural family planning methods

This letter to the editor discusses a review article commenting on the efficacy of contraceptive methods. It takes issue with section focused on natural family planning methods (Billings ovulation method calendar methods symptothermal method etc) and finds fault with the authors not differentiating between the various natural methods. It states that if the authors consider it appropriate to differentiate between the various hormonal contraceptives then differentiation between the natural methods is mandatory.