Hormone releasing $IUDs$ among the following are

What are $\rm {IUDs}$ ? Give its types and effects

Which of the following is a hormone releasing Intra Uterine Device $(IUD)$ ?

Find out the right aspects of lactational amenorrhoea

$I$. Ovulation do not occur during the lactational period

$II$. Chances of the failure of contraception are almost nil upto six months following parturition

$III$. Side effects are almost nil

$IV$. It is a natural method of contraception

$V$. It increases phagocytosis of sperms

Among the following methods, which one has the highest failure rate?