The intrauterine device (IUD) is a long-term birth control method that has demonstrated high contraceptive efficacy and effectiveness due to its high compliance, adherence and persistence of use. The IUD has a global prevalence rate around 14% in women of reproductive age.

Side effects are the main reason for IUD use discontinuation. The most common reasons for copper IUD discontinuation are increased menstrual bleeding, irregular bleeding and dysmenorrhea, whereas in the case of 52mg Levonorgestrel IUD are irregular bleeding and amenorrhea.

In 2014, a new hormonal IUD containing13,5mg of Levonorgestrel was marketed in Spain. There are many studies comparing the two Levonorgestrel IUDs. However, there is any study comparing the IUD 13,5mg Levonorgestrel with classic copper IUDs.

The hypothesis of this trial is that Levonorgestrel (13,5mg) IUD users have a menstrual bleeding pattern with fewer days than Copper 380 mm2 IUD users.

This is a Phase IV, national single-center, randomized 1: 1, single-blind, comparative, parallel controled trial.

Inclusion Criteria:

• Healthy female subject.
• Parous or nulliparous women aged between 18 and 45 years who ask for an IUD as a contraceptive method.
• History of regular cyclic menstrual periods ranged from 21 to 35 days with non-excessive menstrual blood loss.

Exclusion Criteria:

• Absolute contraindications to IUD use, according to the World Health Organization Medical Eligibility Criteria.
• Contraindications to use 13,5 LNG-IUD.
• Anemia.
• Use of short or long-acting preparations containing sex hormones within the 12 weeks before the IUD insertion.
• Known bleeding irregularities.
• Pregnancy or breast-feeding.