Our aim was to study the iodine status impact on thyroid parameters during the first trimester of pregnancy in women free of any current or previous thyroid disease.

Prospective study, on 145 pregnant women (mean age of 29.4±0.5 years) at 10.4±0.2 weeks of gestation. Women with disrupted thyroid balance, who smoke (active smoking confessed) and those followed for thyroid disease or taking medications that interfere with the thyroid gland were excluded. Study protocol: clinical examination, thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), thyroid antibodies (peroxidase antibody and thyroglobulin antibody), and cervical ultrasonography. Statistics tests: collection of data on EPI INFO 5.1, bivariate analysis [the chi-squared test, the Pearson chi-squared test, the Yates corrected chi-squared test, the Wilcoxon chi-squared test (Log rank sum) or Mann-Whitney], the variance analysis method (Anova), the correlation test, significance level P<0.05.

Expressed as median: urinary iodine was 200.0μg/L, iodine deficiency (<150μg/L) was observed in 31.7%, FT4 was 14.1pmol/L, FT3 was 4.9pmol/L, TSH was 1.2mIU/L, and thyroid volume was 6.2mL. We did not find any correlation between urinary iodine excretion and FT4 (r=0.12, P=0.31), FT3 (r=0.19, P=0.12), TSH (r=0.13, P=0.29), and thyroid volume (r=0.10, P=0.38).

Among the pregnant women, in the first trimester, free of any current or previous thyroid disease, 31.7% had an iodine deficiency. There was no correlation between urinary iodine and thyroid parameters.