“…Pregnancy-and local specific reference limits for TSH can be markedly affected by multiple prenalytical and analytical factors, such as age, gender, ethnicity, antithyroid antibodies, iodine status, TSH assays, and alterations on proteins and free fatty acids levels (11). In addition, the non-Gaussian distribution and a high inter individual variation of TSH levels in the normal population confers an extra challenge (12).…”