Importance: Pregnant individuals with polycystic ovary syndrome (PCOS) present with a higher risk of pregnancy complications, including gestational diabetes, preeclampsia, and preterm birth. Myo-inositol supplementation may reduce these risks.
Objective: To determine whether daily supplementation with myo-inositol during pregnancy among individuals with PCOS reduces the risk of a composite outcome of gestational diabetes, preeclampsia, and preterm birth.
Design, setting, and participants: This double-blind, placebo-controlled, randomized trial was conducted at 13 hospitals in the Netherlands. Pregnant individuals with PCOS who were between 8 and 16 weeks' gestation were enrolled between June 2019 and March 2023. Final follow-up was complete on December 27, 2023. Analyses were conducted July 2024.
Interventions: Participants were randomized on a 1:1 basis to receive sachets with either myo-inositol, 2 g, with 0.2 mg of folic acid twice daily (n = 230) or matching placebo with 0.2 mg of folic acid only (n = 234) until delivery.
Main outcomes and measures: The primary outcome was a composite of gestational diabetes, preeclampsia, or preterm birth (before 37 weeks' gestation).
Results: Among 464 participants, the mean (SD) age was 31.5 (3.8) years; 18 participants (3.9%) reported Asian race and 395 (86.1%) reported White race. The prevalence of biochemical hyperandrogenism was higher at baseline in the myo-inositol group than the placebo group (29.0% [53 of 180] vs 18.5% [37 of 193]). A primary outcome event occurred in 25.0% (n = 56) of participants in the myo-inositol group and 26.8% (n = 61) in the placebo group (relative risk, 0.93 [95% CI, 0.68-1.28]; P = .67).
Conclusions and relevance: Myo-inositol supplementation during pregnancy did not reduce the incidence of a composite of gestational diabetes, preeclampsia, or preterm birth in patients with PCOS.
Trial registration: onderzoekmetmensen.nl Identifier: NL67329.078.18.