Multi-center, Open, Randomized, Dose Finding Phase II Study to Investigate Ultra Low Dose Levonorgestrel Contraceptive Intrauterine Systems (LCS) Releasing Different Amounts of Levonorgestrel Compared to MIRENA in Nulliparous and Parous Women in Need of Contraception.

The purpose of this study is to investigate if drug doses lower than the one released from
Mirena® would be as effective for contraception as Mirena®. Subjects participating in the
study will be randomly assigned to be inserted with any of the three different intrauterine
systems (IUSs). The IUSs are nearly alike except that the amount of hormone released from
them is different.