These methods are called natural because they do not require the assumption of chemical contraceptives, nor the insertion of mechanical devices such as an IUD.
They teach you to recognize your fertile period during each menstrual cycle, so that you can avoid sexual intercourse during those days.
They are based on the observation of several indicators (for example, cervical mucus and internal temperature) and their variations, which signal when ovulation occurs.
These methods are rather challenging; there are many rules to follow, they are not highly effective and they require knowledge of and a high level of comfort with your own body. They also require that you take measures to learn the method. For all these reasons, they are not suitable for teenagers. Their effectiveness is considered to be medium-low.
