Iodine Supplementation in Pregnancy in an Iodine-Deficient Region: A Cross-Sectional Survey

Iodineminho Study: Iodine Supplementation and Prevalence of Iodine Deficiency In Pregnant Women

CONTEXT

Iodine is necessary for proper brain development. The prevalence of iodine deficiency in Portuguese pregnant women led the health authorities, in 2013, to recommend iodine supplementation for women in preconception, throughout pregnancy, and during lactation.

OBJECTIVE

This work aimed to assess the effect of iodine supplementation initiated in the preconception or the first trimester of pregnancy on the prevalence of iodine deficiency and maternal thyroid status.

METHODS

An observational prospective cohort study was conducted that followed the thyroid function and iodine status of women recruited during preconception or in the first trimester of pregnancy.

RESULTS

Median urinary iodine concentration (UIC) was significantly higher among women taking iodine supplements (no-supplement group UIC = 63 µg/L; supplement group UIC = 100 µg/L; P = .002) but still below the levels recommended by the World Health Organization. Only 15% of pregnant women had adequate iodine status and 17% showed a UIC of less than 50 µg/L. There was no influence whether iodine supplementation was started during preconception or during the first trimester of gestation (UIC preconception group: 112 µg/L vs UIC pregnancy group: 91 µg/L; P = .569). In the first trimester of pregnancy, total thyroxine levels were lower and free triiodothyronine levels were higher in nonsupplemented women. Thyroglobulin levels were lower in women who started iodine supplementation during preconception compared to nonsupplemented women and women who started iodine supplementation during gestation.

CONCLUSION

In the Minho region of Portugal, fertile women have insufficient iodine intake. Additional public health measures are needed since the current recommendations for iodine supplementation for pregnancy are unsatisfactory to achieve adequate iodine status.

Effects of iodine supplementation on thyroid function parameter: Systematic review and meta-analysis

BACKGROUND

Supplementation is an alternative with potential benefits for the prevention of iodine deficiency in pregnancy.

OBJECTIVE

To evaluate the effects of iodine supplementation on maternal thyroid hormone concentrations and iodine status during and/or before pregnancy.

METHODS

The review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). The search was conducted in the databases: Cochrane, Embase, Pubmed/MEDLINE and Scopus. Studies involving pregnant women of all trimesters who received oral iodine supplementation were included. Study selection was performed in the Rayyan program. Risk of bias was assessed by the Joanna Briggs Institute tool. Meta-analysis was performed in R software version 4.0.4.

RESULTS

Eleven articles with low and moderate risk of bias were included. According to the results of the meta-analysis, supplementation of 200 μg/day of iodine was able to change urinary iodine concentration during pregnancy, thus contributing to adequate intake. When evaluating the period when the intervention started, the best time to start supplementation was prior to pregnancy or in early pregnancy.

CONCLUSION

Daily iodine supplementation had satisfactory effects on iodine status and maternal thyroid hormone concentrations. Although supplementation with 200 µg showed positive effects on iodine status in pregnancy, some studies showed no effect. Prospero Registration: CRD42021249307 (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=249307).

Maternal Urinary Iodine Concentration during Pregnancy and Its Impact on Child Growth and Neurodevelopment: An 11-Year Follow-Up Study

Mild-to-moderate iodine deficiency during pregnancy is prevalent worldwide, but its consequences for maternal and child health are not clear. We aimed to investigate the impact of maternal iodine intake during pregnancy on the child's growth and neurodevelopment. This study involved a cohort of 11-year-old children (n = 70) whose mothers had participated in an iodine intake survey during pregnancy. Gestational, neonatal, anthropometric, intelligence quotient (IQ), and socioeconomic parameters were analyzed according to maternal urinary iodine concentration (UIC). There was a positive linear trend of current height Z-score, full-scale IQ, verbal IQ, family income, maternal education, and a negative trend of neonatal TSH levels with increasing maternal UIC levels. However, regression analysis indicated that maternal UIC was not an independent predictor of any gestational, neonatal, or childhood development parameter. Only maternal school education was positively associated with child height and IQ. In conclusion, we did not find any evidence of a direct effect of maternal iodine intake during pregnancy on the long-term growth and neurodevelopment of children. The results suggest that socioeconomic factors are important confounding factors that affect both maternal iodine intake and child development and must be considered when investigating the association between maternal iodine intake and child outcomes.

Colorimetric and visual determination of iodide ions via morphology transition of gold nanobipyramids

The gold nanobipyramids (Au NBPs) are widely used in the analytical detection of biochemistry due to their unique localized surface plasmon resonance (LSPR) properties. In our developed approach, I^- in kelp was detected by etching Au NBPs in the presence of IO₃^-. Under acidic conditions, IO₃^- reacted rapidly with I^- to form I₂, subsequently I₂ reacted with I^- to form the intermediate I₃^-. In the presence of CTAB, Au NBPs were etched by I₂ derived from I₃^-, resulting in a decrease in the aspect ratio of Au NBPs, to form a significant blue shift of LSPR longitudinal peak and color variation of colloid which changed from blue-green to magenta and could be employed to quantitatively detect the concentration of I^- with the naked eye. A linear relationship can be found between the LSPR peak changes with the I^- concentration in a wide range from 4.0 μM to 15.0 μM, and the sensitive limit of detection (LOD) was 0.2 μM for UV-vis spectroscopy and the obvious color changes with a visual LOD was 4.0 μM for the naked eye. Benefiting from the high specificity, the proposed colorimetric detection of I^- in kelp samples was achieved, indicating the available potential of the colorimetric detection for the determination of I^- in real samples. What's more, this detection procedure was time-saving and could avoid tedious procedures.

Preconception Counseling in Patients with Hypothyroidism and/or Thyroid Autoimmunity

Preconception counseling is an essential tool for preventing adverse pregnancy outcomes associated with thyroid dysfunction. The high prevalence of thyroid disease among women of reproductive age, and the increased risk of adverse pregnancy outcomes associated with thyroid dysfunction, emphasize the necessity for well-established screening and treatment criteria in the preconception period. We therefore conducted a literature review for relevant information on the screening, diagnosis and treatment of subclinical and overt hypothyroidism in women seeking pregnancy. While screening for thyroid disease is recommended only in the presence of risk factors, iodine supplementation should be recommended in most regions, with higher doses in areas with severe deficiency. Known hypothyroid women should be counseled about increasing their levothyroxine dose by 20–30% in the case of suspected or confirmed pregnancy (missed menstrual cycle or positive pregnancy test). Treating subclinical hypothyroidism appears to be beneficial, especially in the presence of autoimmunity or in patients undergoing artificial reproductive techniques. Regarding the management of TPOAb negative SCH women or euthyroid women with positive TPOAb, further research is necessary in order to make evidence-based recommendations.