Maternal Myo‐Inositol Intake and Congenital Heart Defects in Offspring: A Population‐Based Case–Control Study

Objective To investigate associations between maternal periconceptional (three months prior through the third pregnancy month) myo‐inositol intake and the odds of selected congenital heart defects in offspring. Design A population‐based case–control study using the National Birth Defects Prevention Study (NBDPS) database. Setting United States. Population or Sample Women with singleton live births without major birth defects (controls) and women with singleton live births, stillbirths, or terminations with selected nonsyndromic congenital heart defects (CHD; cases). Methods Descriptive analyses, logistic regression models, ascertainment of myo‐inositol intake from supplements and food using a shortened food frequency questionnaire and survey. Main Outcome Measures Odds of CHD. Results 11 752 cases and 11 415 controls were included. Compared to women not taking myo‐inositol supplements, women with any supplemental intake were less likely to have a pregnancy with the selected congenital heart defects as a group (adjusted odds ratio [aOR] = 0.79; 95% confidence interval [CI] 0.66–0.94) or with septal defects alone (aOR = 0.61; 95% CI 0.46–0.81). Compared to women with low total myo‐inositol intake from food or supplements, women with high total myo‐inositol intake (≥ 500 mg/day) were less likely to have a pregnancy with the selected CHD as a group (aOR = 0.88; 95% CI 0.84–0.93) or conotruncal defects (aOR = 0.87; 95% CI 0.79–0.96); left ventricular outflow tract defects (aOR = 0.87; 95% CI 0.78–0.96); right ventricular outflow tract defects (aOR = 0.85; 95% CI 0.77–0.95); or atrial septal defects (aOR = 0.91; 95% CI 0.83–0.99). Conclusions An inverse association was observed between maternal myo‐inositol intake during the periconceptional period and the odds of selected CHDs in offspring.