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Endocrine Abstracts (2012) 29 S52.1

ICEECE2012 Symposia Thyroid & Pregnancy (3 abstracts)

Outcome of the controlled antenatal thyroid screening study

J. Lazarus


Cardiff University, Cardiff, UK.


Fetal brain development depends on thyroid hormone and children born to mothers with low thyroid hormone levels have decreased cognitive function. Nineteen per cent of children born to mothers known to have a high TSH during gestation had an IQ <80 compared to 5% of children born to mothers known to have normal TSH levels in pregnancy (P<0.001; Haddow et al. 1999).

We conducted a randomized trial of antenatal hypothyroidism screening with selective treatment and assessment of childhood cognitive function.

Pregnant women were randomized at about 12 weeks’ gestation into a screen or control group. Blood was collected for thyroid stimulating hormone (TSH) and free thyroxine (FT4) measurements before 16 weeks. In the screen group measurements were made immediately; control group serum was stored and measurements made shortly after delivery. Women with TSH levels >97.5th centile and/or FT4 levels <2.5th centile were designated positive and women in the screen group were prescribed levo-thyroxine. IQ measurements were performed on children of women with positive results aged three by psychologists unaware of whether the women were in the screen or control group.

Out of 21 846 women tested, 390 in the screen group and 404 in the control group tested positive. Nineteen percent of women required levo-thyroxine dose adjustment. The mean IQ’s in the screen and control positive groups were 99.2 and 100.0; a difference of 0.8 (95% CI −1.1 to 2.6, P=0.403, intention-to-treat analysis) respectively, and the proportions with IQ <85 were 12.1 and 14.1% respectively; a difference of 2.1% (95% CI −2.6 to 6.7%, P=0.39). An on-treatment analysis showed no significant difference.

Antenatal screening and treatment for hypothyroidism from about 12 weeks of pregnancy showed no benefit in childhood cognitive function assessed at age three. (Funded by The Wellcome Trust UK and Compagnia di San Paulo Turin).

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details are unavailable.

Volume 29

15th International & 14th European Congress of Endocrinology

European Society of Endocrinology 

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