Follow-up study on the change of thyroid function of subclinical hypothyroidism women during the whole pregnancy

【Objective】 To explore the dynamic changes of thyroid function of the pregnant women with subclinical hypothyroidism during the pregnancy,and to observe the outcome of subclinical hypothyroidism in these women during the pregnancy.【Methods】85 pregnant women with subclinical hypothyroidism were followed up regularly from G12 to G36 and the interval was 4 weeks.All the subjects underwent the planned thyroid tests regularly.Serum TSH,TT4,FT4,TT3,FT3,TPOAb and TgAb were measured.【Results】Serum TSH decreased to nadir at G12(compared with G6,P 0.01) and then increased gradually.Serum TT4 increased to 133.58 nmol/L at G12,and remained the high level to G32.Serum FT4 decreased gradually from the first trimester till the end of the pregnancy(each point from G16 to G36,P 0.01).Serum TT3 and FT3 increased gradually in the first trimester,and stayed in the high level thereafter.68.2% of pregnant women with subclinical hypothyroidism before G7 still presented subclinical hypothyroidism during the pregnancy(group A).And the TSH level in only 31.8% of pregnant women with subclinical hypothyroidism decreased into the normal intervals during follow-up period(group B).The pregnant outcomes and the indexes of newborns are not different between group A and group B.【Conclusion】The levels of serum TSH and thyroid hormones fluctuate during the different phases of pregnancy.The thyroid function can restore normal levels in less than one third of pregnant women with subclinical hypothyroidism diagnosed in early pregnancy.