Hypothyroidism during pregnancy: Controversy over screening and intervention

Abstract

Thyroid hormones are critical for foetal neurological development and maternal health. Maternal hypothyroidism during pregnancy is associated with adverse impact on health of the mother as well as the progeny. Reduced thyroid hormone levels predispose the child to develop mental retardation and cognitive delay in early life. In the mother, hypothyroidism during pregnancy is associated with spontaneous abortion, placental abruption, preterm delivery and hypertensive disorders. Therefore, screening and therapeutic intervention is justified to prevent foetal as well as maternal co-morbidities. In view of impact of such a large-scale screening and intervention program on limited healthcare resources, it is debatable if a targeted rather than universal screening program will result in comparable outcomes. In addition, there is an ongoing debate regarding best evidence-based practice for the management of isolated hypothyroxinaemia, subclinical hypothyroidism and euthyroid women with autoimmune hypothyroidism. We have carried out a review of the literature; firstly, to determine whether universal screening for asymptomatic women in early pregnancy would be cost-effective. Secondly, we have retrospectively reviewed the literature to analyse the evidence regarding the impact of therapeutic intervention in women with subclinical hypothyroidism.

Keywords: Targeted screening; Thyroid peroxidase antibodies; Isolated hypothyroxinaemia; Spontaneous abortion; Overt hypothyroidism; Placental abruption; Universal screening; Hypothyroidism during pregnancy; Subclinical hypothyroidism; Autoimmune hypothyroidism

Core tip: Hypothyroidism during pregnancy poses a significant health challenge as it is associated with adverse health outcomes for mother as well as the child. There is evidence that supports increased maternal and neonatal morbidity, even in absence of a clinically overt maternal hypothyroid state. However, in view of limited available healthcare resources, the jury is still divided regarding use of universal vs targeted screening programs in pregnant women. In addition, there is a lack of consensus regarding the best management approach for isolated hypothyroxinaemia and subclinical hypothyroidism. Keeping these contentious issues in mind, we have carried out a review of the literature.