Taken through pregnancy, myo-inositol did not prevent complications
In 464 women with polycystic ovary syndrome, 4 g daily left gestational diabetes, preeclampsia and preterm birth combined at 25.0% against 26.8% on placebo.
What the study found
Four grams of myo-inositol a day changed nothing in pregnancy
Four grams of myo-inositol daily through pregnancy left the combined rate of gestational diabetes, preeclampsia and preterm birth at 25.0% against 26.8% on placebo, in 464 women with polycystic ovary syndrome. An earlier Cochrane pooling had cut gestational diabetes risk roughly in half.
The caveat · All 13 sites were Dutch
This tested prevention during pregnancy in women who already had polycystic ovary syndrome, so it says nothing about inositol taken before conception for ovulation or cycles. All 13 sites were Dutch and 86.1% of participants reported White race. Baseline hyperandrogenism ran against the treated arm, 29.0% versus 18.5%.
What we don't know
Earlier, mostly Italian trials suggested myo-inositol in pregnancy roughly halved gestational diabetes; a later, adequately powered Dutch trial found no effect. The two are not of equal quality, which is why the null carries more weight.