IUD) is thought to act immediately by inhibiting sperm and ovum viability or preventing implantation.2 The LNG-IUS has a different contraceptive mechanism of action that relies on hormonal effects on the endometrium, cervical mucus and uterotubal transport, and thus has a delayed onset.2,3 This is the rationale for advising additional contraception for 7 days if a LNG-IUS is inserted after Day ...