Purpose of the study is the evaluation of the tolerability (both local and systemic) and the clinical efficacy (in terms oocytes recovered) of subcutaneously versus intramuscularly administered Merional® (IBSA, Lugano - CH) in patients undergoing controlled ovarian hyperstimulation (COH) in an ART programme (IVF).

Inclusion Criteria:

• Female patients
• aged between 20 and 40 years
• undergoing ovarian stimulation for the purposes of oocyte retrieval in an assisted conception programme
• Body Mass Index (BMI) 20-28 kg/m2
• early follicular phase FSH level < 9 IU/l.

Exclusion Criteria:

• ascertained or presumptive hypersensitivity to the active principle and/or their ingredients
• primary ovarian failure
• ovarian cysts or enlargement not due to polycystic ovarian syndrome
• oocyte donation
• abnormal bleeding of undetermined origin
• patients who have exhibited poor response or requiring doses of more than 300 IU daily in previous treatment cycles or those who have received similar therapies (previous treatment cycles) in the 30 days prior to the beginning of the present study
• uncontrolled thyroid or adrenal dysfunction
• neoplasia
• severe impairment of the renal and/or hepatic functions
• diabetes and active thrombophlebitis, cardiopathies and epilepsy
• presence of clinically significant systemic disease or any contraindication of being pregnant and/or carrying out a pregnancy to term
• presence of any anatomical abnormality of the reproductive system
• being pregnant or breastfeeding
• menopause