Exposure to arsenic during pregnancy and newborn mitochondrial DNA copy number: A birth cohort study in Wuhan, China

Arsenic (As) is a widely distributed environmental chemical with potentially different toxicities. However, little is known about the impact of maternal As exposure on newborn mitochondrial DNA copy number (mtDNAcn), which may lie on the pathway linking As exposure to adverse health impacts. We aimed to explore whether maternal As exposure was associated with newborn mtDNAcn. We conducted a birth cohort study of 762 mother-infant pairs in Wuhan, China, 2013–2015. Cord blood mtDNAcn was determined using qPCR. Maternal urinary As levels in each trimester were quantified by ICP-MS. Multiple informant models were used to examine the associations of repeated urinary As levels with cord blood mtDNAcn. The median urinary As levels in the first, second, and third trimesters were 17.2 μg/L, 16.0 μg/L, and 17.0 μg/L, respectively. In the multivariate model, each doubling increase in the first-trimester urinary As level was associated with a 6.6% (95% CI: −12.4%, −0.5%) decrease in cord blood mtDNAcn. The highest versus lowest quintile of first-trimester urinary As level was associated with a 19.0% (95% CI: −32.9%, −2.2%) lower cord blood mtDNAcn. No significant associations of urinary As levels in the second and third trimesters with cord blood mtDNAcn were observed. The inverse relationship between first-trimester urinary As level and cord blood mtDNAcn was more pronounced among female infants. First-trimester As exposure was related to decreased cord blood mtDNAcn. The potential health impacts of decreased mtDNAcn in early life need to be further clarified. •First study to assess the associations of trimester-specific As exposure with newborn mtDNAcn.•First-trimester As exposure was associated with decreased newborn mtDNAcn.•The estimated inverse relationship was more pronounced among female infants.