One study showed significantly higher PBDE levels in umbilical cord blood and breast milk samples from mothers with a history of thyroid disease compared to healthy mothers [44], and another study suggested a correlation between congenital hypothyroidism and PBDEs in the serum [45], while Jacobson et al. found higher TSH and lower T4 concentrations among toddlers [46]. Here, CD4 is linked to congenital hypothyroidism.