Clinical Edge

Summaries of Must-Read Clinical Literature, Guidelines, and FDA Actions

Thyroid Hormone Treatment in Pregnant Women

BMJ; ePub 2017 Jan 25; Maraka, et al

A small percentage of pregnant women with subclinical hypothyroidism received thyroid hormone treatment, despite the association between thyroid hormone treatment and decreased risk of pregnancy loss, a recent study found. In a national US cohort of 5,405 pregnant women with subclinical hypothyroidism, researchers found:

  • 16% received thyroid hormone treatment.
  • Thyroid hormone treatment was associated with decreased risk of pregnancy loss but also with increased risk of important complications such as preterm delivery, gestational diabetes, and pre-eclampsia.
  • The benefit of thyroid hormone use on pregnancy loss was observed only among women with pretreatment thyroid stimulating hormone concentrations of 4.1 to 10.0 mIU/L, but not 2.5-4.0 mIU/L.


Maraka S, Mwangi R, McCoy RG, et al. Thyroid hormone treatment among pregnant women with subclinical hypothyroidism: US national assessment. [Published online ahead of print January 25, 2017]. BMJ. doi:10.1136/bmj.i6865.