Gastro

new england journal of medicine
The
established in 1812

february 9, 2012

vol. 366

no. 6

Antenatal Thyroid Screening and Childhood Cognitive Function
John H. Lazarus, M.D., Jonathan P. Bestwick, M.Sc., Sue Channon, D.Clin.Psych., Ruth Paradice, Ph.D., Aldo Maina, M.D., Rhian Rees, M.Sc., Elisabetta Chiusano, M.Psy., Rhys John, Ph.D., Varvara Guaraldo, M.S.Chem., Lynne M. George,H.N.C., Marco Perona, M.S.Chem., Daniela Dall’Amico, M.D., Arthur B. Parkes, Ph.D., Mohammed Joomun, M.Sc., and Nicholas J. Wald, F.R.S.

A BS T R AC T
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 providedblood samples for measurement of thyrotropin and free thyroxine (T4). 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 T4 levels below the 2.5th percentile, or both were considered a positive screeningresult. 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

From the Centre for Endocrine and Diabetes Sciences, Cardiff School of Medicine (J.H.L., R.R., A.B.P.); the Department ofChild Psychology, St. David’s Hospital (S.C., R.P.); and the Department of Medical Biochemistry, University Hospital of Wales (R.J.) — all in Cardiff, United Kingdom; Wolfson Institute of Preventive Medicine, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London (J.P.B., L.M.G., M.J., N.J.W.); and Azienda Ospedaliera Ospedale Infantile Regina Margherita–Sant’Anna, Turin, Italy (A.M., E.C., V.G., M.P., D.D.). Address reprint requests to Dr. Lazarus at the Centre for Endocrine and Diabetes Sciences, Cardiff University School of Medicine, Heath Park, Cardiff, Wales CF14 4XN, United Kingdom, or at lazarus@cf.ac.uk. This article (10.1056/NEJMoa1106104) was updated on April 26, 2012, at NEJM.org. N Engl J Med 2012;366:493-501.
Copyright © 2012Massachusetts Medical Society.

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 thechildren 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 to6.7; 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.)
n engl jmed 366;6 nejm.org february 9, 2012

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The New England Journal of Medicine Downloaded from nejm.org on October 10, 2012. For personal use only. No other uses without permission. Copyright © 2012 Massachusetts Medical Society. All rights reserved.

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