Abstract： Objetive To investigate the obstetrical and neonatal outcomes of pregnant women with hypothyroidism or subclinical hypothyroidism.Methods One hundred and sixty-eight pregnant women with clinical or subclinical hypothyroidism during pregnancy,including 9 controlled hypothyroidism,29 uncontrolled hypothyroidism and 130 subclinical hypothyroidism,were enrolled in this study.The general clinical information,obstetrical complications and neonatal outcomes of these pregnant women were compared with that of 180 healthy pregnant women who delivered during the same period.Results Compared with control group,there were no significant differences in the levels of serum free triiodothyronine( FT3 ),free thyroxine ( FT4 ),thyrotropin-stimulating hormone (TSH) in the controlled hypothyroidism group in the third trimester [(3.68 ±1.11 ) pmol/L vs (3.19 ±0.33) pmol/L,(15.48 ±4.14) pmoL/L vs (13.95 ± 1.68) pmol/L,1.87 mU/L vs 1.76 mU/L,P ＞0.05].However,in the second and third trimester,the levels of FT3,FT4 in the uncontrolled hypothyroidism group were lower,while the levels of TSH were higher than in control group [(2.71 ±0.80) pmol/L vs (3.14 ± 0.34) pmoL/L,(10.94 ± 2.68) pmol/L vs (14.25 ±2.01) pmol/L,5.62 mU/L vs 2.28 mU/L,( 2.34 ± 0.70 ) pmol/L vs ( 3.19 ± 0.33 ) pmol/L,( 10.16 ± 1.65 ) pmol/L vs (13.95 ± 1.68) pmoL/L,7.13 mU/L vs 1.76 mU/L,t =2.754～9.15,P ＜0.01],the levels of TSH in the subclinical hypothyroidism were higher than in control group ( t =18.28,18.57,P ＜0.01 ).There was no adverse perinatal outcome of neonate happened in controlled hypothyroidism group.In contrast,the incidences of adverse perinatal outcomes and complications in the uncontrolled hypothyroidism group were higher than that in the control group ( 17.2％ vs 2.8％,37.9％ vs 5.6％,x2 =11.47,28.97,P ＜0.01 ).Compared with that of control group,the incidences of adverse obstetrical outcomes in pregnant women with subclinical hypothyroidism were increased (40.0％ vs 5.6％,x2 =52.97,P ＜ 0.01 ).Conclusions The rate of adverse obstetrical outcomes and complications is increased in women with clinical or subclinical hypothyroidism.But the incidence of adverse outcomes would decrease if hypothyroidism is controlled by treatment.