When a woman is over 40 years old, her blood becomes sticky and she is prone to blood clots. Especially women who have been smoking for a long time are more prone to thrombotic diseases over 40 years old. Yohtek is a highly effective progestin, and after the use of this drug, it will increase the viscosity in the blood and make it more prone to thrombotic diseases. Therefore, it is not recommended to apply this drug to women over 40 years old to avoid the risk of thrombotic diseases. 40 years old and above if there is a requirement for contraception, condoms can be used to prevent pregnancy, or IUDs can be placed, these methods of contraception are more reliable.