Once the uterus detects the presence of a foreign body inside it, it begins to release leukocytes and prostaglandin, causing a harmful effect on sperm, eggs and zygotes.
In addition, the continuous release of hormones by the hormonal IUD causes:
- The cervical mucus to become thick, making it difficult for sperm to move.
- The lining of the uterus decreases.
- Ovulation does not occur.
All this causes the IUD to prevent pregnancy.