This study is the first study investigating the combined intrauterine administration of LNG (levonorgestrel) and IND (indomethacin). It is a combined proof-of-concept (PoC) and dose finding (DF) study in pre-menopausal women. It is designed to investigate the pharmacodynamics (PD) of BAY 987443 (i.e. IUS (intrauterine system) releasing LNG and IND), as well as pharmacokinetics (PK) of both active substances, safety and tolerability. In this study, Jaydess, as an LNG-only IUS, will be used as a comparator.

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)