Assessment of Iodofolic Supplementation on Thyroid Function in Pregnant Women with Iodine Sufficient Status and their Infants in Birjand

Background: Maintaining iodine at sufficient levels is necessary throughout the pregnancy to prevent adverse outcomes in infants. This study aimed to assess iodofolic supplementation's impact on thyroid function in women at the end of the third trimesters of gestation. Methods: This case-control study was conducted on 130 pregnant women in the Birjand, east of Iran, during the period from August 2017 to February 2019. We assessed iodofolic supplementation effect in the women at the first trimesters of gestation and followed them at the end of the third trimesters and also their infants on days 3-5. Serum samples were obtained from women and infants for measuring levels of thyroid-stimulating hormone (TSH). Urinary iodine concentration (UIC) was also determined at the end of the third trimester. Results: The median serum TSH concentration in the folic acid consumed group (3.26 +/- 1.91) did not significantly differ from another group (2.98 +/- 1.41), (p = 0.68). There is also no considerable difference in the mean serum TSH concentration between infants born from mothers who consumed folic acid in the first trimester of pregnancy and another group (p = 0.50). The TSH concentration in all infants was below 5 mu M/L. The significant difference in the mean of UIC was also not observed between pregnant women in the folic acid consumed group (188.02 +/- 105.38) and iodofolic consumed group (225.77 +/- 130.26), (p = 0.13). Conclusion: Iodine intake in our study was sufficient according to the WHO recommendation and idofolic supplementation was not emphasized.