PERgoveriS In Stratified Treatment for Assisted Reproductive Technique

This is a multicenter, multi-national, randomized, open-label comparative trial. After screening, the subjects will start down-regulation treatment on Day 21-22 of the cycle. Down-regulation treatment will start within 2 months following the screening visit. The routine long luteal phase protocol for gonadotropin-releasing hormone (GnRH) agonist treatment will be followed. Once down-regulation has been confirmed, a pregnancy test will be performed just before randomization and start of recombinant human follicle-stimulating hormone (r-hFSH) treatment to rule out any pre-existing pregnancy. If the result is negative, the subject will be randomly assigned to one of the two treatment arms of the trial:

* GONAL-f®: (Liquid Pen; 300 international unit \[IU\] of per day) stimulation Day 1-5 followed by Pergoveris® (vial/powder, 300 IU per day) from stimulation Day 6 and until required recombinant human chorionic hormone (r-hCG) criterion is met. The dose can be adjusted from stimulation Day 6 (increased or decreased) based upon the subject's ovarian response and according to the center's standard practice.
* Pergoveris®: (vial/powder, 300 IU per day) from stimulation Day 1 and until required r-hCG criterion is met. The dose can be adjusted from stimulation Day 6 (increased or decreased) based upon the subject's ovarian response and according to the center's standard practice.

Randomization across the two treatment arms will be kept balanced in a 1:1 ratio. Follicular development will be monitored according to the center's standard practice by ultrasound (US) and/or estradiol (E2) levels, until the protocol r-hCG requirement is met (i.e., at least one follicle greater than or equal to \[\>=\] 18 millimeter \[mm\] and two follicles \>=16 mm). After this, a single injection of r-hCG will be administered in order to induce final oocyte maturation.

At a time of 34-38 hours after r-hCG administration, oocytes will be recovered vaginally under US monitoring. Oocytes will then be fertilized in vitro and embryos replaced 2-5 days after oocyte recovery. Ovum pick up (OPU), in vitro fertilization (IVF), embryo transfer (ET) and luteal support will be performed as per center's standard practice.

A post-treatment safety visit will be performed for all subjects who received r-hCG (pregnant and non- pregnant) on Day 15-20 post-hCG. For subjects who have withdrawn from treatment (i.e. after starting Pergoveris® or Gonal-f® but before hCG is given) this visit will take place 20-30 days after their first Pergoveris® or Gonal-f® treatment injection (excluding pregnancy testing).


Eligibility Criteria:
Inclusion Criteria:

* Be a female subject justifying an in vitro fertilization and embryo transfer (IVF/ET) treatment
* Be between her 36th and 40th birthday (both included) at the time of the randomization visit
* Have early follicular phase (Day 2-4) serum level of basal follicle stimulating hormone (FSH less than or equal to (=\<)12 IU/L) measured in the center's local laboratory during the screening period (that is within 2 months prior to down-regulation start)
* A body mass index (BMI) less than (\<) 30 kilogram per square meter (kg/m\^2)
* Have a regular spontaneous ovulatory menstrual cycle between 21 and 35 days in length
* Be willing and able to comply with the protocol for the duration of the trial
* 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
* 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
* Other protocol specified inclusion criteria could also apply.

Exclusion Criteria:

* Had \>= 2 previous ART cycles with a poor response to gonadotrophin stimulation defined as =\< 6 mature follicles and/or =\<4 oocytes collected in any previous IVF cycle or previous cycles with a hyper response defined as \>= 25 oocytes retrieved
* 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
* Had previous severe ovarian Hyperstimulation Syndrome (OHSS)
* Polycystic ovary syndrome (PCOS; Rotterdam criteria) to reduce the risk of the occurrence of OHSS
* Any contraindication to being pregnant and/or carrying a pregnancy to term
* History of 3 or more miscarriages (early or late miscarriages) due to any cause
* A clinically significant systemic disease
* Known infection with Human Immunodeficiency Virus (HIV), Hepatitis B or C virus in the trial subject or her male partner
* Known allergy or hypersensitivity to human gonadotrophin preparations
* Entered previously into this trial or simultaneous participation in another clinical trial.
* Pregnancy and lactation period
* Participation in another clinical trial within the past 30 days
* Other protocol specified inclusion criteria could also apply.