Supplementation With Human Chorionic Gonadotropin (hCG) During Controlled Ovarian Stimulation With Recombinant Follicle-stimulating Hormone (FSH) for In Vitro Fertilisation

Inclusion Criteria: 1. Females with indication for COS and IVF; 2. Age between 25-37 years; 3. BMI \>18 and \< 30 kg/m2; 4. A regular menstrual cycle between 24 and 35 days and presumed to be ovulatory; 5. Two ovaries; 6. Tubal or unexplained infertility, including endometriosis stage I/II; 7. A uterus consistent with expected normal function (e.g. no clinically interfering uterine fibroids) documented by transvaginal ultrasound at the screening; 8. Male partner with sperm quality compatible with fertilization via IVF procedure or previous clinical pregnancy; 9. Early follicular phase serum FSH levels of 1-12 IU/l; 10. Early follicular phase total antral follicle (2-10mm) count ≥ 6; 11. Confirmation of down-regulation before randomisation by transvaginal ultrasound; 12. Willing and able to sign informed consent. Exclusion Criteria: 1. History of or current PCOS, endometriosis stage III/IV or severe male factor requiring ICSI; 2. History of severe ovarian hyperstimulation syndrome (OHSS); 3. Presence of unilateral or bilateral hydrosalpinx at ultrasound; 4. More than three previously COS cycles; 5. Previous poor response on an IVF-cycle, defined as \>20 days of gonadotrophin stimulation, cancellation due to limited follicular response or less than four follicles of ³15 mm diameter; 6. Previous IVF cycle with unsuccessful fertilization, defined as fertilisation of £20% of the retrieved oocytes; 7. History of recurrent miscarriage; 8. FSH\>12IU/L or LH\>12UI/L (early follicular phase); 9. Contraindications for the use of gonadotropins or GnRH analogues; 10. Recent history of current epilepsy, HIV infection, diabetes or cardiovascular gastrointestinal, hepatic, renal or pulmonary disease; 11. Pregnancy, lactation or contraindication to pregnancy; 12. Current past (last 12 months) abuse of alcohol or drugs; 13. History of chemotherapy (except for gestational conditions) of radiotherapy; 14. Undiagnosed vaginal bleeding; 15. Tumours of the ovary, breast, adrenal gland, pituitary or hypothalamus and malformation of sexual organs incompatible with pregnancy; 16. Abnormal karyotyping of the patient (if karyotyping is performed); 17. Hypersensitivity to any trial product.