Compared with the reference group (euthyroidism and TPO Ab−), subjects with subclinical hyperthyroidism and TPO Ab+/− had a higher risk of LBW in multivariate analyses (OR: 1.94, 95% CI: 1.06, 3.55), but not in univariate analyses (Supplemental Table 5 and Table 4). Here, TPO is linked to hyperthyroidism.