The aim of this study was to evaluate the effect of oral L-carnitine supplementation during controlled ovarian stimulation (COS) in patients with polycystic ovary syndrome (PCOS) in a double-blind randomized clinical trial. The eligible patients with PCOS diagnosis (on the basis of Rotterdam criteria) who referred to Royan Research Institute for IVF / ICSI treatment cycles will be evaluated.

The study protocol was approved by the Institutional Review Board and Ethics Committee of Royan institute. Prior to the onset of ovarian stimulation, patients will be allocated randomly into two groups according to block randomization method. The methodologist will give the doctor a code according to the randomization list, which corresponds to the code on the drug's box, and the drug box will be delivered to the patient. The COS procedure in all the study participate will be same by using a flexible regimen of GnRH antagonist with E2 priming. In the experimental group, the women received 3 tablet of L-carnitine daily (L-carnitine® tablet 1000 mg, Karen Pharmaceutical Company, Iran) from day 2 of the previous menstrual cycle until pregnancy test day. The patients in control group will receive 3 placebo tablets for 8 weeks. All the placebo tablets were produced by Karen company (Tehran, Iran), which is approved by the Food and Drug Administration of Iran. The appearance of the placebo was indistinguishable in color, shape, size, and smell from L-carnitine tablets. Ovarian stimulation will start with a maximum dose of 150 units of rFSH (Gonal -F: Serono Laboratories Ltd, Geneva, Switzerlan), from the second or third day of the spontaneous or discontinued progesterone menstrual cycle and the monitoring transvaginal ultrasound was performed and then if the follicle is observed, start with 13 injections of GnRH antagonist (Cetrotide®, 0.25 mg cetrorelix acetate, Serono, Inc) and will be continued until the oocyte triggering day. From the seventh day of the cycle, the dose of rFSH will be determined according to the rate of ovarian response by vaginal ultrasonography two days in advance. If you see at least two follicles 18 mm in size or more, the final stimulation of oocyte maturation will be done and 34- 36 hour after that the ovum pickup will be conducted. Subsequently ICSI or IVF will be done with standard procedure. In the present study, the markers of insulin metabolism (fasting glucose and insulin) and lipid profiles (LDL, HDL, cholesterol and triglyceride) as well as body mass index and weight were measured at the baseline of the study (before starting L-carnitine supplementation) as well as 6 weeks later on the ovum pick up day.The outcome evaluators were also blinded to the random allocation process and type of treatment.The primary and secondary outcomes were compared between the two groups using appropriate statistical tests.

Inclusion Criteria:

• Patients between 20 to 37 years old, presenting with primary or secondary infertility following regular intercourse for at least 1 year and diagnosed with polycystic ovary syndrome (PCOS) according to Rotterdam's criteria who had received two to three failures of IUI cycle therapy were included. The diagnosis was based on a complete history taking, physical examination and a paper documented complete infertility work-up within the previous 6 months

Exclusion Criteria:

1. Patients diagnosed with hyperprolactinemia, diabetes mellitus, epilepsy
2. Patients treated with special diet, medication supplement (ovuboost), metformin before or during ovarian stimulation
3. History of pelvic surgery on ovaries and uterus.
4. Presence of submucosal and intramural fibroids larger than 5 cm or the presence of uterine polyps and congenital uterine malformations.
5. The cause of severe male infertility (TESE, PESA).

L-carnitine and placebo drugs can be identified only by special codes determined by a statistics specialist. The participant, care provider, investigator and outcome assessor are unaware of the type of study groups.