Fetal-Maternal Outcomes of Isolated Hypothyroxinemia in Pregnancy

ABSTRACT

Purpose: The prevalence of isolated hypothyroxinemia (IH) ranges between 1.3 and 30%. Thus, the goal of our study was to determine the prevalence of IH in our region, and to explain the maternal-fetal effects of IH.
Material and Method: One hundred-ninety-six pregnant women without previous thyroid disease were included. Six pregnant women did not complete the study due to abortion during the first trimester. All of these patients were euthyroid. Hypothyroidism was detected in three and hyperthyroidism was detected in 2 pregnant women, who were excluded from the study. The remaining 185 pregnant women underwent free T3, free T4, thyroid stimulating hormone, antithyroid peroxidase antibody, antithyroglobulin antibody, and urinary iodine measurements during the three trimesters.
Results: We detected IH among 38% of pregnant females in our population. When the assessment was performed for each trimester; IH was not detected in any patient at the 1st trimester, IH was detected in 59/185 and in 50/185 pregnant women at the 2nd and the 3rd trimesters, respectively. While 13 of these patients detected at the last trimester had new onset IH, in 37 of patients, IH was present even during the 2nd trimester. Even though iodine deficiency was higher in IH group, the difference was statistically insignificant. Fifty percent of the 50 patients with IH who returned for the post-partum examination were noted to have improved thyroid function.
Discussion: No negative effect of IH was observed on fetal development and obstetric outcomes. In the light of current knowledge, therapy is not recommended for patients with IH. The effect of iodine supplementation on fT4 decrease has not been shown to IH patients should also be given iodine supplementation should be given and the doseshould be the same as recommended to pregnant women.