A prospective study of early pregnancy essential metal(loid)s and glucose levels late in the second trimester.

CONTEXT: Studies suggest many essential trace metal(loid)s are involved in glucose metabolism, but the associations among pregnant women are unclear.

OBJECTIVE: To assess associations between early pregnancy plasma zinc, selenium, copper and molybdenum and blood glucose levels later in the 2nd trimester.

DESIGN: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies - Singleton cohort, a prospective cohort study between July 2009 and January 2013.

SETTING: 12 academic research hospitals in the U.S.

PATIENTS: 1857 multi-racial non-obese healthy women.

MAIN OUTCOME MEASURES: Blood glucose levels from 1-hour 50-g gestational load test (GLT) at 24 to 28 weeks of gestation.

RESULTS: Higher concentrations of 1st trimester copper were associated with higher glucose levels from GLT (i.e. per 50% increase in copper concentrations was related to 4.9 mg/dL higher glucose level, 95% CI: 2.2, 7.5) adjusted for maternal socio-demographic characteristics and reproductive history. In contrast, per 50% increase in molybdenum concentrations were associated with 1.2 mg/dL lower mean glucose levels (95% CI: -2.3, -0.1). The magnitudes of these associations were greater at the upper tails of glucose level distribution based on quantile regressions of the 10th, 50th, and 90th percentiles.

CONCLUSIONS: Higher copper and lower molybdenum concentrations could increase the risk of glucose dysregulation during pregnancy, with women at higher risk of GDM potentially affected to a greater extent. Further work is needed to understand the mechanisms involved with early pregnancy essential metal(loid)s in order to inform clinical diagnosis and prevention for glucose intolerance during pregnancy.