Newborn screening for congenital hypothyroidism: worldwide coverage 50 years after its start

Background: Congenital hypothyroidism (CH) is a preventable cause of neurodevelopmental delay in children, detectable by newborn screening (NBS) programs for CH. Since NBS for CH was started in Canada in 1974, numerous countries have successfully implemented this public health strategy. However, in 2014, only 29.3% of newborns worldwide were screened by NBS for CH. Objective: This study aimed to assess the implementation of new NBS programs for CH over the past decade, and screening methods and coverage rates of current programs. In addition, it sought to update the worldwide iodine status. Methods: We reviewed literature data on NBS programs for CH and their coverage rates for each country, using PubMed, Embase and Google searches. Results: Currently, 29.6% of children worldwide are screened for CH. Europe, North America, Oceania, China, Japan and Israel have efficient programs with optimal coverage. Recently, some countries of Central and Western Asia have implemented NBS programs for CH, and coverage has increased in several Asian countries. South America has also seen substantial improvements in coverage. In contrast, almost none of the African countries has widespread screening programs, but some attempts with pilot studies and local initiatives have been witnessed. Global iodine sufficiency has improved, with 149 of 193 countries achieving adequate iodine levels by 2023. Conclusions: Over the past decades, several countries have launched NBS programs for CH or conducted pilot studies, and the coverage of most existing NBS programs has increased. Nevertheless, approximately 70% of newborns worldwide still lack access to NBS for CH, predominantly in African and Asian countries, accounting for a significant part of annual births.