1000 women with infertility who are already decided to be treated with ICSI will be subjected to full history taking and clinical examination. On the second day of menstruation serum FSH, LH, Prolactin and Oestradiol will be assessed and the antral follicular count (AFC) will be assessed using a vaginal ultrasound scan. AFC will be defined as the number of follicles measuring 3-10mm.

All patients will have standard pituitary down-regulation followed by (Human menopausal gonadotrophin (HMG) stimulation until the day of (Human chorionic gonadotrophin (HCG) administration. On the day of HCG administration, ovarian ultrasound scan will be performed using a transvaginal probe and the Preovulatory follicle count (PC) will be assessed, (PFC) is defined as number of follicles measuring≥16mm. Follicular sensitivity index (FSI) will be calculated as: (FSI =PFC*10000/AFC*Total dose of FSH)

Our study is observational, we are observing data from routine measurements during IVF/ICSI. Our study does not assess IVF/ICSI as an intervention, we are evaluating the role of FSI which is calculated by observing routine measurements during the IVF/ICSI procedure.

All women fulfilling the inclusion criteria will be invited to participate in the study. A written informed consent will be taken and only women signing the consent will be included in the study. Patients included in the study will be subjected to full history taking and clinical examination including general, abdominal and gynecological examination. This will be followed by a vaginal ultrasound scan to assess uterus, ovaries and any pelvic masses.

All women will go through the usual IVF/ICSI procedure explained below, our aim is to observe the antral follicle count, the pre-ovulatory count, the total dose of FSH and calculate the FSI then correlating this with pregnancy.

All patients will have standard pituitary down-regulation protocol with GnRHa (Triptorelin 0.1mg, Decapeptyl® Ferring, Germany) day 7 after ovulation of previous cycle or on day 21 of the oral contraceptive cycles. GnRHa will be continued for 2 weeks. Human menopausal gonadotrophin(HMG) (Merional ®IBSA) 150-300 IU/day will be administered until the day of HCG administration.

On the day of HCG administration, ovarian ultrasound scan will be performed using a transvaginal probe and the Preovulatory follicle count (PC) will be assessed, (PFC) is defined as number of follicles measuring≥16mm. FSI will be calculated as: (FSI =PFC*10000/AFC*Total dose of FSH) FSI values will be classified into 3 categories: low, medium and high the 3 groups will be compared regarding the clinical pregnancy rate, number of retrieved oocytes, number and quality of embryos The procedure will be cancelled if less than 3 follicles 16-20 mm in size are present 12 days after starting FSH despite doses reaching 450 IU. The cycle will be also cancelled if there is risk of ovarian hyperstimulation like massive ovarian enlargement or serum estradiol exceeds 3000pg/L Transvaginal oocyte retrieval will be performed 34-36 h after the administration of HCG. Oocytes will be fertilized either via IVF or ICSI based on the couple's history. Fertilization will be assessed 16-18 h after IVF or ICSI. Embryo transfers will be performed 3 days after oocyte retrieval. No more than three embryos per patient will be transferred; vaginal tablets containing progesterone (Prontogest® IBSA) administered 400 mg/day as luteal support from the day of the oocyte retrieval. Clinical pregnancy will be defined as Visualization of an intrauterine gestational sac 5 weeks after embryo transfer.

Inclusion Criteria:

• Both ovaries are present
• Day 2 FSH <10 mIU/L
• Day 2 Estradiol <50 pg/L

Exclusion Criteria:

• Polycystic ovarian syndrome (PCOS)
• Abnormalities affecting the uterine cavity
• Uncontrolled diabetes
• Allergy to gonadotrophins
• Cancelled cycles during the study

1000 women with infertility without polycystic ovarian syndrome who are already decided to be treated with ICSI will be recruited from Cairo university hospitals and Dar Al-Teb subfertility centre.