The potential benefit of levothyroxine treatment during pregnancy: another step forward

Abstract

Thyroid hypofunction during pregnancy is associated with a wide range of adverse pregnancy and child outcomes such as miscarriage, premature delivery, abnormal birth weight and suboptimal offspring neurodevelopment. Thyroid autoimmunity, reflected by thyroperoxidase antibody (TPOAb) positivity, is the most important risk factor for thyroid hypofunction. During pregnancy, TPOAb-positive women have higher TSH and lower FT4 concentrations and a higher risk of overt and subclinical hypothyroidism than TPOAb-negative women (1, 2). Intriguingly, TPOAb positivity is associated in several observational studies with a higher risk of adverse outcomes including miscarriage, premature delivery and gestational diabetes, even in euthyroid women (2, 3, 4, 5, 6, 7). Such studies suggest potential adverse effects of thyroid autoimmunity on pregnancy outcome. However, the mechanisms underlying these associations, as well as causality of the associations, remain to be elucidated. In this context, the study by Nazarpour et al. in the current issue of the European Journal of Endocrinology is a very valuable contribution.