Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Meta-Analysis
. 2021 Feb 10;11(2):e043505.
doi: 10.1136/bmjopen-2020-043505.

Insufficient iodine nutrition status and the risk of pre-eclampsia: a systemic review and meta-analysis

Charles Bitamazire Businge  1   2 , Anthony Usenbo  3 , Benjamin Longo-Mbenza  4 , A P Kengne  2   5
Affiliations
Meta-Analysis

Insufficient iodine nutrition status and the risk of pre-eclampsia: a systemic review and meta-analysis

Charles Bitamazire Businge et al. BMJ Open. .

Abstract

Background: Although subclinical hypothyroidism in pregnancy is one of the established risk factors for pre-eclampsia, the link between iodine deficiency, the main cause of hypothyroidism, and pre-eclampsia remains uncertain. We conducted a systematic review to determine the iodine nutrition status of pregnant women with and without pre-eclampsia and the risk of pre-eclampsia due to iodine deficiency.

Methods: MEDLINE, EMBASE, Google Scholar, Scopus and Africa-Wide Information were searched up to 30th June 2020. Random-effect model meta-analysis was used to pool mean difference in urinary iodine concentration (UIC) between pre-eclamptic and normotensive controls and pool ORs and incidence rates of pre-eclampsia among women with UIC <150 µg/L.

Results: Five eligible studies were included in the meta-analysis. There was a significant difference in the pooled mean UIC of 254 pre-eclamptic women and 210 normotensive controls enrolled in three eligible case-control studies (mean UIC 164.4 µg/L (95% CI 45.1 to 283.6, p<0.01, I2 >50)). The overall proportions of pre-eclampsia among women with UIC <150 µg/L and UIC >150 µg/L in two cross-sectional studies were 203/214 and 67/247, respectively, with a pooled OR of 0.01 (95% CI 0 to 4.23, p=0.14, I2 >50) for pre-eclampsia among women with UIC >150 µg/L. The overall incidence of pre-eclampsia among women with UIC <150 µg/L and UIC >150 µg/L in two cohort studies was 6/1411 and 3/2478, respectively, with a pooled risk ratio of 2.85 (95% CI 0.42 to 20.05, p=0.09, I2 <25).

Conclusion: Although pre-eclamptic women seem to have lower UIC than normotensive pregnant women, the available data are insufficient to provide a conclusive answer on association of iodine deficiency with pre-eclampsia risk.

Prospero registration number: CRD42018099427.

Keywords: epidemiology; maternal medicine; nutrition & dietetics.

PubMed Disclaimer

Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
Study selection flow chart.
Figure 2
Figure 2
Forest plot showing the mean difference in urinary iodine concentration of normotensive and pre-eclamptic mothers.
Figure 3
Figure 3
(A) Forest plot showing the odds of pre-eclampsia among women with urinary iodine concentration (UIC) <150 µg/L. (B) Forest plot showing the log odds of pre-eclampsia among women with UIC >150 µg/L (p=0.068, Tau2=9.8, I2=88.94%).
Figure 4
Figure 4
Forest plot showing the risk of pre-eclampsia among women with urinary iodine concentration <150 µg/L (designated as experimental group). Pooled risk ratio=2.89 (0.42 to 20.05), p=0.09.
Figure 5
Figure 5
Funnel plot for the studies selected for the analysis of the mean difference in urinary iodine concentration of pre-eclamptic women and normotensive counterparts.
Figure 6
Figure 6
Funnel plots for publication bias in the studies selected for the analysis of the mean difference urinary iodine concentration of pre-eclamptic women and normotensive counterparts. The two imputed studies are represented by empty circles.
Figure 7
Figure 7
Funnel plot for the studies selected for the analysis of the risk of pre-eclampsia among women with urinary iodine concentration <150 µg/L.
See this image and copyright information in PMC

References

    1. Abalovich M, Gutierrez S, Alcaraz G, et al. . Overt and subclinical hypothyroidism complicating pregnancy. Thyroid 2002;12:63–8. 10.1089/105072502753451986 - DOI - PubMed
    1. Khanam M, Ilias M. Study of thyroid hormonal status in preeclamptic patients. Med Today 2013;25:63–6. 10.3329/medtoday.v25i2.17922 - DOI
    1. Wilson KL, Casey BM, McIntire DD, et al. . Subclinical thyroid disease and the incidence of hypertension in pregnancy. Obstet Gynecol 2012;119:315–20. 10.1097/AOG.0b013e318240de6a - DOI - PubMed
    1. Lazarus JH Screening for thyroid dysfunction in pregnancy: is it worthwhile? J Thyroid Res 2011;2011:397012. 10.4061/2011/397012 - DOI - PMC - PubMed
    1. Jameson LJ, Mandel SJ, Weetman AP. Ch 405- disorders of the thyroid gland : Kasper DL, Hauser SL, Jameson JL, et al., Principles of internal medicine 19th ed. New York: McGraw Hill Education, 2015: 2283–308.

Publication types

LinkOut - more resources