Fetal Growth Is Associated with Amniotic Fluid Antioxidant Capacity, Oxidative Stress, Minerals and Prenatal Supplementation: A Retrospective Study.

Background: Associations of antioxidants in prenatal over-the-counter multivitamin-mineral (OTC MVM) supplements with in-utero oxidative stress (OS), antioxidant capacity, and fetal growth are limited. Our objectives were to determine if five fetal ultrasound measurements [biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), and estimated fetal weight] were associated with OTC MVM supplements and with minerals, biomarkers of OS, and total antioxidant capacity in amniotic fluid (AF).

Methods: For this retrospective study, 176 pregnant women who had undergone age-related amniocentesis for genetic testing were included. Questionnaires recorded prenatal OTC MVM supplementation (yes, no). Ultrasound measurements for early (16-20 weeks) and late (32-36 weeks) gestation were extracted from medical charts. AF concentrations for 15 minerals and trace elements and OS biomarkers in AF [nitric oxide (NO), thiobarbituric acid-reactive substances (TBARS), and ferric-reducing antioxidant power (FRAP)] were measured at 12-20 weeks of gestation. Associations of AF minerals, OS biomarkers, and ultrasound measures were analyzed using multiple linear regressions.

Results: Positive associations were observed between AF TBARS and seven AF minerals/elements (calcium, copper, magnesium, nickel, strontium, zinc and iron). At 16-20 weeks, AF copper, nickel, strontium, and selenium were positively associated with BPD, HC, AC, and FL, respectively, NO was positively associated with FL, and FRAP was inversely associated with estimated weight. At 32-36 weeks, calcium was positively associated with BPD and chromium and arsenic were negatively with HC. At 16-20 weeks, higher AF FRAP was inversely associated with FL and this exposure continued to be inversely associated with estimated weight at 32-36 weeks.

Conclusions: Concentrations of AF minerals, trace elements and biomarkers of OS and in-utero antioxidant capacity were linked to specific ultrasound measurements at different stages of gestation, suggesting a complex interplay among in utero OS, antioxidant capacity, OTC MVM supplements, and fetal growth.