What are the advantages of natural methoods of contraception over artificial methods ?

Explanation

Artificial methods of contraception have certain drawbacks e.g. IUDs cause occasional haemorrhage or infections, while combined oral pills containing progesterone-estrogen combination may cause breast tenderness, break through bleeding, weight gain, etc. On the other hand the natural methods do not involve use of any contraceptive or chemical or surgery so have no side-effects but have high chance of failure. Natural methods include rhythm period, coitus interruptus and lactational amenorrhoea.