(N/A) The devices inserted by doctors or expert nurses in the uterus through the vagina are called Intra Uterine Devices $(IUDs)$.
$IUDs$ are of three main types:
$(a)$ Non-medicated $IUDs$: e.g.,Lippes loop.
$(b)$ Copper-releasing $IUDs$: e.g.,$CuT$,$Cu7$,Multiload $375$.
$(c)$ Hormone-releasing $IUDs$: e.g.,Progestasert,$LNG-20$.
Effects of $IUDs$:
$1$. $IUDs$ increase phagocytosis of sperms within the uterus.
$2$. The $Cu$ ions released by copper-releasing $IUDs$ suppress sperm motility and the fertilizing capacity of sperms.
$3$. The hormone-releasing $IUDs$ make the uterus unsuitable for implantation and the cervix hostile to sperms.
$IUDs$ are ideal contraceptives for females who want to delay pregnancy and/or space children.