CONSORT Randomized Controlled Trial in Assisted Reproductive Technology

Inclusion Criteria: 1. Female subjects justifying an in-vitro fertilization (IVF)/embryo transfer (ET) treatment 2. Have a male partner with semen analysis within the past 6 months prior to randomization considered adequate to proceed with regular insemination or intracytoplasmic sperm injection (ICSI) according to the center's standard practice. If these criteria are not met, the subject can only be entered if donor sperm will be used 3. Between her 18th and 35th birthday (35 not included) at the time of the randomization visit 4. Body mass index (BMI) lower than 30 kilogram per square meter (kg/m\^2) where the BMI is calculated according to the formula 5. Have a regular spontaneous ovulatory menstrual cycle between 21 and 35 days in length 6. Have an early follicular phase (Day 2-4) serum level of basal FSH lower than or equal to 12 International Unit per Liter (IU/L) measured in the center's local laboratory during the screening period (i.e. within 2 months prior to down-regulation start) 7. Presence of both ovaries 8. Normal uterine cavity, which in the investigator's opinion is compatible with pregnancy 9. Have a negative cervical papanicolaou (PAP) test within the last 6 months prior to randomization 10. Have at least 1 wash-out cycle (defined as greater than or equal to 30 days since the last dose of clomiphene citrate or gonadotrophin treatment) since the last ART cycle and/or clomiphene citrate or gonadotrophin treatment prior to starting gonadotropin releasing hormone (GnRH) agonist therapy 11. Willing and able to comply with the protocol for the duration of the trial 12. Have given written informed consent, prior to any trial-related procedure not part of normal medical care, with the understanding that consent may be withdrawn by the subject at any time without prejudice to her future medical care Exclusion Criteria: 1. Have greater than or equal to 2 previous ART cycles with a poor response to gonadotrophin stimulation (defined as lower than or equal to 5 mature follicles and/or lower than or equal to 3 oocytes collected) or have greater than or equal to 2 previous ART cycles with a hyper response (defined as greater than or equal to 25 oocytes retrieved) 2. Any medical condition, which in the judgment of the investigator may interfere with the absorption, distribution, metabolism or excretion of the drug. In case of doubt, the subject in question should be discussed with Merck Serono's Medical responsible 3. Have previous severe ovarian hyperstimulation syndrome (OHSS) 4. Polycystic ovary syndrome (PCOS; Rotterdam criteria) to reduce the risk of the occurrence of OHSS 5. Presence of endometriosis requiring treatment 6. Uterine myoma requiring treatment 7. Any contraindication to being pregnant and/or carrying a pregnancy to term 8. Extra-uterine pregnancy within the last 3 months prior to screening 9. History of 3 or more miscarriages (early or late miscarriages) due to any cause 10. Tumors of the hypothalamus and pituitary gland 11. Ovarian enlargement or cyst of unknown etiology 12. Ovarian, uterine or mammary cancer 13. A clinically significant systemic disease 14. Known infection with Human Immunodeficiency Virus (HIV), Hepatitis B or C virus in the trial subject or her male partner, 15. Abnormal gynecological bleeding of undetermined origin 16. Known allergy or hypersensitivity to human gonadotrophin preparations, 17. Any active substance abuse or history of drug medication or alcohol abuse in the past 5 years prior to the screening visit 18. Entered previously into this trial or simultaneous participation in another clinical trial