The goal of this clinical trial is to learn if Estetrol/Drospirenone inhibit ovulation in quick-starting method. It will also learn about the safety of Estetrol/Drospirenone. The main questions it aims to answer are:

Does Estradiol valerate/Dienogest inhibit ovulation inferior to Ethinyl estradiol/Gestodene when starting on Day 7-9 of menstrual cycle? What are the impacts of Estradiol valerate/Dienogest on ovarian activities when starting on Day 7-9 of menstrual cycle? How does the cervical mucus change when starting Estradiol valerate/Dienogest on Day 7-9 of menstrual cycle? What are the adverse effects when starting Estradiol valerate/Dienogest on Day 7-9 of menstrual cycle? Researchers will compare Estradiol valerate/Dienogest to Ethinyl estradiol/Gestodene to see if Estradiol valerate/Dienogest inhibit ovulation in quick-starting method.

Take Estradiol valerate/Dienogest or Ethinyl estradiol/Gestodene starting on day 7-9 of menstrual cycle then every day for 1 pack of the pills.

Visit the clinic on day 1-2, day 7-9, and then every 2-7 days according to ultrasound finding (ovarian activities) until completing of pills to investigate

• Transvaginal ultrasound
• Cervical mucus
• Serum hormonal profiles.

Inclusion Criteria:

• Women aged 18 - 45 years old
• Body mass index 18-30 kg/m²
• Menstrual interval within 24 - 38 days
• Absence of history of estrogen or progestin allergy and Absence of these compatibles with U.S. medical eligibility criteria category 3 - 4
• Consent to use condom as contraception or have been sterilized

Exclusion Criteria:

• History of estrogen, progestin or testosterone use within 3 months
• Current pregnant or within 3 months of breastfeeding
• Having ovarian cyst(s) or tumor(s)
• Being a cervical cancer patient or having precancerous cervical lesion