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
Randomized Controlled Trial
. 2012 Feb 9;366(6):493-501.
doi: 10.1056/NEJMoa1106104.

Antenatal thyroid screening and childhood cognitive function

John H Lazarus  1 , Jonathan P Bestwick, Sue Channon, Ruth Paradice, Aldo Maina, Rhian Rees, Elisabetta Chiusano, Rhys John, Varvara Guaraldo, Lynne M George, Marco Perona, Daniela Dall'Amico, Arthur B Parkes, Mohammed Joomun, Nicholas J Wald
Affiliations
Randomized Controlled Trial

Antenatal thyroid screening and childhood cognitive function

John H Lazarus et al. N Engl J Med. .

Erratum in

  • N Engl J Med. 2012 Apr 26;366(17):1650

Abstract

Background: Children born to women with low thyroid hormone levels have been reported to have decreased cognitive function.

Methods: We conducted a randomized trial in which pregnant women at a gestation of 15 weeks 6 days or less provided blood samples for measurement of thyrotropin and free thyroxine (T(4)). Women were assigned to a screening group (in which measurements were obtained immediately) or a control group (in which serum was stored and measurements were obtained shortly after delivery). Thyrotropin levels above the 97.5th percentile, free T(4) levels below the 2.5th percentile, or both were considered a positive screening result. Women with positive findings in the screening group were assigned to 150 μg of levothyroxine per day. The primary outcome was IQ at 3 years of age in children of women with positive results, as measured by psychologists who were unaware of the group assignments.

Results: Of 21,846 women who provided blood samples (at a median gestational age of 12 weeks 3 days), 390 women in the screening group and 404 in the control group tested positive. The median gestational age at the start of levothyroxine treatment was 13 weeks 3 days; treatment was adjusted as needed to achieve a target thyrotropin level of 0.1 to 1.0 mIU per liter. Among the children of women with positive results, the mean IQ scores were 99.2 and 100.0 in the screening and control groups, respectively (difference, 0.8; 95% confidence interval [CI], -1.1 to 2.6; P=0.40 by intention-to-treat analysis); the proportions of children with an IQ of less than 85 were 12.1% in the screening group and 14.1% in the control group (difference, 2.1 percentage points; 95% CI, -2.6 to 6.7; P=0.39). An on-treatment analysis showed similar results.

Conclusions: Antenatal screening (at a median gestational age of 12 weeks 3 days) and maternal treatment for hypothyroidism did not result in improved cognitive function in children at 3 years of age. (Funded by the Wellcome Trust UK and Compagnia di San Paulo, Turin; Current Controlled Trials number, ISRCTN46178175.).

PubMed Disclaimer

Figures

Figure 1
Figure 1
Randomization and Follow-up of the Study Participants.
Figure 2
Figure 2. Relative Risk of an IQ Score below Specified Cutoff Scores in the Screening Group as Compared with the Control Group, According to the Intention-to-Treat Analysis
I bars indicate 95% confidence intervals.
Figure 3
Figure 3. Relative Risk of an IQ Score below Specified Cutoff Scores in the Screening Group as Compared with the Control Group, According to the On-Treatment Analysis
A total of 308 women (79%) were found to have complied with treatment (i.e., they had a decrease of at least 10% in the thyrotropin level and an increase of at least 10% in the free thyroxine level). I bars indicate 95% confidence intervals.
See this image and copyright information in PMC

Comment in

References

    1. de Escobar GM, Obregón MJ, del Rey FE. Maternal thyroid hormones early in pregnancy and fetal brain development. Best Pract Res Clin Endocrinol Metab. 2004;18:225–48. - PubMed
    1. Pharoah PO, Buttfield IH, Hetzel BS. Neurological damage to the fetus resulting from severe iodine deficiency during pregnancy. Lancet. 1971;1:308–10. - PubMed
    1. Velasco I, Carreira M, Santiago P, et al. Effect of iodine prophylaxis during pregnancy on neurocognitive development of children during the first two years of life. J Clin Endocrinol Metab. 2009;94:3234–41. - PubMed
    1. Berbel P, Mestre JL, Santamaría A, et al. Delayed neurobehavioral development in children born to pregnant women with mild hypothyroxinemia during the first month of gestation: the importance of early iodine supplementation. Thyroid. 2009;19:511–9. - PubMed
    1. Haddow JE, Palomaki GE, Allan WC, et al. Maternal thyroid deficiency during pregnancy and subsequent neuropsychological development of the child. N Engl J Med. 1999;341:549–55. - PubMed

Publication types

MeSH terms

Associated data