References

The copper-bearing intrauterine device (Cu-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 7.3 Although progestogen hormone can delay ovulation, the levels released from the LNG-IUS are insufficient to act in the same way as oral progestogen-only EC. Therefore, as stated in CEU Guidance, we recommend that only copper-bearing devices should be used for EC.