Dietary soy consumption during early pregnancy is not associated with the development of thyroid dysfunction

Data were collected through questionnaire from 505 women enrolled during early pregnancy.Based on soy intake frequency,the subjects were divided into three groups:frequent (three or more times per week),conventional ( more than twice per month but less than three times per week),and occasional ( two or fewer times per month).Serum TSH and FT4 were measured by chemiluminescence immunoassay.The urinary concentrations of two primary isoflavones (daidzein and genistein) and creatinine were further assessed in 95 subjects from the three groups.The percentages of frequent,conventional,and occasional consumers were 18.6％,62.6％,and 18.8％,respectively.No difference was found in age,medical records,family history of thyroid diseases,serum FT4,TSH,and prevalence of thyroid dysfunctions among three groups. Both urinary daidzein and genistein levels were significantly higher in the frequent consumers compared with the other two groups.No correlations were found between urinary isoflavone levels and serum FT4 or TSH.These findings suggest that dietary soy consumption during early pregnancy seems not to be associated with the development of thyroid dysfunction. Key words: Daidzein; Genistein; lsoflavone; Pregnancy; Thyroid