Abstract: Objective:To analyze the correlation between subclinical thyroid disease and missed abortion for reducing the missed abortion rate.Methods:Seventy-one patients with missed abortion and 80 normal pregnant women were divided into the observation group and control group,respectively.The serum levels of free triiodothyronine(FT3),free thyroxine(FT4),thyroid stimulating hormone(TSH),thyroglobulin antibody(TGAb) and thyroid microsomal antibody(TMAb) between two groups were compared.The pregnant outcome in two groups was followed up.Results:There was no statistical difference in the serum levels of FT3,FT4,TSH,TGAb and TMAb between two groups(P>0.05).The incidence rate of subclinical thyroid disease in observation group was higher than that in control group(P<0.01),the subclinical hypothyroidism(TSH elevated type) was the main type.The differences of thyroid autoantibody and incidence of hyperthyroidism between two groups were not statistically significant(P>0.05).Conclusions:The subclinical hypothyroidism(TSH elevated type) is correlated with the missed abortion rate,the subclinical hyperthyroidism and thyroid autoantibody are not significantly related to the missed abortion.The impact of subclinical thyroid disease on the missed abortion mainly happens on early pregnancy.