BACKGROUND

Ovulation induction treatment with metformin, either alone or in combination with clomiphene citrate (CC), remains controversial even though previous randomized trials have examined this.

METHODS

A double blinded multi-centre randomized trial was undertaken including 171 women with anovulatory or oligo-ovulatory polycystic ovary syndrome. Women with high body mass index (BMI) > 32 kg/m² received placebo (‘standard care’) or metformin; women with BMI ≤ 32 kg/m² received CC (‘standard care’), metformin or both. Treatment continued for 6 months or until pregnancy was confirmed. Primary outcomes were clinical pregnancy and live birth.

RESULTS

For women with BMI > 32 kg/m², clinical pregnancy and live birth rates were 22% (7/32) and 16% (5/32) with metformin, 15% (5/33) and 6% (2/33) with placebo. For women with BMI ≤ 32 kg/m², clinical pregnancy and live birth rates were 40% (14/35) and 29% (10/35) with metformin, 39% (14/36) and 36% (13/36) with CC, 54% (19/35) and 43% (15/35) with combination metformin plus CC.

CONCLUSIONS

There is no evidence that adding metformin to ‘standard care’ is beneficial. Pregnancy and live birth rates are low in women with BMI > 32 kg/m² whatever treatment is used, with no evidence of benefit of metformin over placebo. For women with BMI ≤ 32 kg/m² there is no evidence of significant differences in outcomes whether treated with metformin, CC or both.

ClinicalTrials.gov number NCT00795808; trial protocol accepted for publication November 2005: Johnson, Aust N Z Journal Obstet Gynaecol 2006;46:141–145.