Mechanisms of Uterine Fluid Absorption During Early Pregnancy ( ELF Study)

Inclusion Criteria: 1. Subject must be a healthy woman between the ages of 18 and 45 years. 2. Women with diagnosed endometriosis or infertility (cases). 3. Women without a diagnosis of endometriosis or infertility (controls). 4. Subject must have regular menstrual cycles. 5. Subject must have a body mass index (BMI) between 18 and 40. 6. Subject must be or have been sexually active or have had a previous vaginal exam that used a speculum. 7. Subject must be able to understand and provide consent to procedures and use/disclosure of protected health information. 8. No history of Chlamydia trachomatis, Mycoplasma genitalium, Neisseria gonorrhoeae, hepatitis B, and HIV. 9. For IVF study subjects, a minimum endometrial thickness of 7mm at the time of sample collection. Exclusion Criteria: 1. Pregnant women. 2. Study subjects with endometrial cancer. 3. Study subjects with a history of endometrial ablation. 4. Study subjects with undiagnosed uterine bleeding. 5. Women with reproductive diseases that affect the endometrium (such as fibroids or uterine polyps that distort endometrial cavity). 6. Study subjects with an intrauterine device (IUD).