The aim of study was to investigate whether pre-treatment with metformin before and during IVF increases the live birth rate compared to placebo in women with sonographic evidence of polycystic ovaries (PCO), but without any clinical manifestations of polycystic ovary syndrome (PCOS).

Inclusion Criteria:

• Women attending with ovulatory PCO due to undergo IVF/ICSI treatment.
• First or second cycle of IVF/ICSI.
• If previously on metformin, a minimum one month washout period was required.
• Polycystic ovaries diagnosed by ultrasound presence of ≥12 follicles measuring 2-9 mm in diameter in at least one ovary and/or increased ovarian volume (≥10 ml).
• Written informed consent.

Exclusion Criteria:

• Clinical manifestations of PCOS, including any of the following:

  1. Oligo- or amenorrhoea with cycles ≥42 days apart.
  2. Anovulation with mid-luteal progesterone <16 nmol/L.
  3. Biochemical hyperandrogenism with serum testosterone ≥3.5 nmol/L and/or free androgen index >5 (FAI = [total testosterone/SHBG] x 100).
  4. Clinical hyperandrogenism with hirsutism or acne requiring treatment at least weekly.

• Age >38 years.

• BMI >35 kg/m2.

• Basal FSH >12 IU/L.

• Liver disease or ALT >80 IU/L.

• Renal disease, or creatinine >130 nmol/L.

• Alcoholism or drug abuse.

• Diabetes mellitus (evaluated by fasting glucose >6.7mmol/L).

• Per oral steroid treatment in last month.

• Cimetidine, anticoagulation, erythromycin, or other macrolides in last month.

• Hyperprolactinemia (Prolactin >700 mIU/L).

• Abnormal thyroid function tests (TSH outside of laboratory normal range).

• Congenital adrenal hyperplasia.