Does the IUD prevent pregnancy from the beginning or does it kill the sperm, and what is the legitimacy of its use and other means of contraception?

The use of IUDs (intrauterine devices) for contraception has become widespread. Their mechanism relies on irritating the uterine wall, which prevents the fertilized egg from implanting. There is no religious issue with this, as long as the egg has not yet implanted in the uterus and is not attached to it. As for the use of an IUD itself, it is permissible in cases of need or necessity if no other method is available, or if the woman inserts it herself, or her husband does, or if there is a medical condition that necessitates uncovering the 'awrah (private parts) and the insertion of the IUD is part of this examination. It should be noted that IUDs have other health precautions such as bleeding and pain, and they do not prevent pregnancy 100%. As for other contraceptive methods, it is permissible to use them temporarily for a valid purpose, provided that they do not cause harm to the woman.