Contraception

Inclusion Criteria

- Agreement to use an acceptable non-hormonal method of contraception (i.e. male or female condom with or without spermicide; cap, diaphragm or sponge with spermicide) when sexually active. This applies during the pre-treatment cycle and directly following the treatment period until the end of the follow-up period. This is not required if safe contraception is achieved by a permanent method, such as bilateral fallopian tube blockage of the subject or vasectomy of the partner(s).
 - Age at screening: 18–45 years inclusive
 - Body mass index (BMI) at screening: ≥ 18 and ≤ 32 kg/m²
 - No clinically relevant abnormal findings in the pre-treatment endometrial biopsy
 - Adequate venous access (for frequent blood sampling)

Exclusion Criteria

- Menstrual disorders with unknown reason (not e.g. oligomenorrhea, hypomenorrhea amenorrhea due to hormonal treatment; not irregularities occurring during menarche). In case it is suspected that the woman is peri-menopausal, she should be excluded.
 - Use of short-acting hormonal contraceptives/preparations containing sex hormones (oral, transdermal, intravaginal, IUS) during the pretreatment cycle
 - Use of long-acting preparations containing sex hormones within the 40 weeks before the first screening examination (any long-acting injectable or implant)
 - History of known or presence of suspected or known malignant tumors, especially any breast cancer, cervical carcinoma in situ or other progestin-sensitive cancer
 - History of skin reactions, or other allergic-type reactions or known hypersensitivity reactions after taking aspirin, IND or other NSAIDs or to LNG, or any excipients of the IUSs
 - Regular use of corticosteroids, irrespective of route of administration
 - Known asthma bronchiale and aspirin-sensitive asthma
 - Current or recurrent pelvic inflammatory disease
 - Abnormal cervical smear within the last 6 month prior to screening
 - Acute genital infection
 - Known current thyroid disorders which require treatment (subjects with an euthyroid struma who do not need any treatment can participate)