ObjectiveTo establish a normal reference value range of specific thyroid function in pregnant women corresponding to Beckman reagent in Chengdu.MethodsWe randomly selected 120 non-pregnant women and 445 pregnant women who underwent routine examinations at the First Affiliated Hospital of Chengdu Medical College from November 2016 to June 2017; tested for free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH) in serum; used SPSS 24.0 to calculate the bilateral limit of each index (Section 2.5, 97. 5 Quot); established the normal range of Beckman reagent.ResultsThe reference ranges of FT3, FT4, and TSH in the first, second, and third trimester of pregnancy were 4.41–6.33, 4.17–6.12, and 3.86–6.39 pmol/L; 7.64–14.63, 6.62–13.69, and 6.62–12.51 pmol/L; 0.21–3.62, 0.16–4.35, and 0.89–4.88 mU/L; respectively. There was no significant difference in serum TSH between the first and second trimester (P>0.05), and neither between the first and second trimesters and the controls in serum FT3 (P>0.05). The differences in serum FT3, FT4, and TSH among the rest of trimesters, and between each trimester and the normal control group were statistically significant (P<0.05). There was a significant correlation between TSH and FT4 in the early and middle stages of pregnancy (r=–0.277, –0.392, P<0.01).ConclusionThe reference value of FT3, FT4, and TSH in pregnant women with Beckman reagent was significantly different from that in non-pregnant women.