Myo-inositol and fertility: what the evidence says

What does the evidence say about myo-inositol while trying to conceive?

1. A meta-analysis of ten randomized trials covering 362 women on inositol found significantly improved ovulation rate and more frequent menstrual cycles compared with placebo, while no included study evaluated live birth or miscarriage. 1
2. The systematic review commissioned for the 2023 update of the international evidence-based PCOS guidelines concluded that the evidence supporting inositol in PCOS is limited and inconclusive, and advised shared decision-making that acknowledges that uncertainty. 2
3. That review pooled 30 trials covering 2,230 participants and found signals for myo-inositol or D-chiro-inositol on some metabolic measures and potential benefit from D-chiro-inositol for ovulation, with no apparent effect on other outcomes. 2
4. Compared head to head with metformin, myo-inositol likely causes fewer gastrointestinal adverse events, and those events are typically mild and self-limited, while reproductive outcomes were likely no different between the two. 2
5. Standard prepregnancy advice is to bring every medication, vitamin, and herbal product in its original packaging to the visit, because some are not appropriate in pregnancy and your clinician needs the labels to judge them. 3

What to know about myo-inositol while trying to conceive

• The research lives here, in the months before conception, and it is narrower than the marketing suggests. A BJOG meta-analysis of ten randomized trials found improved ovulation rate and more frequent menstrual cycles versus placebo, but no included study reported live birth or miscarriage. That gap is the honest headline.
• There is no established role for myo-inositol in the second trimester and no pregnancy dosing guidance to work from. If you were taking it before conception, the question to put to your clinician is simply whether to continue, not how much.
• Same situation, and the same conversation. Bring the actual product, since inositol supplements often combine myo-inositol with D-chiro-inositol in varying ratios, and the two forms were studied separately in the trials that exist.