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:

1. Does Estetrol/Drospirenone inhibit ovulation inferior to Ethinyl estradiol/Gestodene when starting on Day 7-9 of menstrual cycle?
2. What are the impacts of Estetrol/Drospirenone on ovarian activities when starting on Day 7-9 of menstrual cycle?
3. How does the cervical mucus change when starting Estetrol/Drospirenone on Day 7-9 of menstrual cycle?
4. What are the adverse effects when starting Estetrol/Drospirenone on Day 7-9 of menstrual cycle?

Researchers will compare Estetrol/Drospirenone to Ethinyl estradiol/Gestodene to see if Estetrol/Drospirenone inhibit ovulation in quick-starting method.

Participants will:

Take Estetrol/Drospirenone 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

1. Transvaginal ultrasound
2. Cervical mucus
3. Serum hormonal profiles.

Inclusion Criteria:

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

Exclusion Criteria:

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

Female