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Thyroid hormone treatment can reduce risk of pregnancy loss

Pregnant women with mild thyroid problems who receive thyroid hormone treatment have a decreased risk of pregnancy loss, suggest US researchers. 

Pregnant women with mild thyroid problems who receive thyroid hormone treatment have a decreased risk of pregnancy loss, suggest US researchers. 


The researchers analysed data from 5,405 pregnant women with
subclinical hypothyroidism. Picture: iStock

To determine the potential safety and effectiveness of thyroid hormone treatment among this group, the researchers analysed data from 5,405 pregnant women with subclinical hypothyroidism, defined as untreated thyroid stimulating hormone (TSH) with levels of 2.5 to 10 mlU/L. 

Women treated with the thyroid hormone were compared with untreated women for risk of pregnancy loss and other pregnancy-related adverse outcomes. 

Fact

Subclinical hypothyroidism affects an estimated 15% of pregnancies in the US and 14% in Europe. 

Overall, 16% of women in the study received thyroid hormone treatment. Compared with untreated women, the researchers found that treated women had a lower risk of pregnancy loss but a higher risk of preterm delivery, gestational diabetes and pre-eclampsia. 

Higher levels, more benefit

The associated benefit of thyroid hormone treatment on pregnancy loss was seen only among women with TSH levels of 4.1 to 10mlU/L before treatment, and not those with levels of 2.5 to 4mlU/L. 

‘Continuing to offer thyroid hormone treatment to decrease the risk of pregnancy loss in women with TSH concentrations of 4.1-10.0 mlU/L is reasonable,’ the study authors said. 

But they added that, due to the possible increased risk of other adverse events, treatment may need to be withheld in those with TSH concentrations of 2.5-4.0 mlU/L and the guidelines revised. 


Spyridoula M et al (2017) Thyroid hormone treatment among pregnant women with subclinical hypothyroidism: US national assessment. BMJ. http://dx.doi.org/10.1136/bmj.i6865

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