Prevalence of Congenital Hypothyroidism in Neonates of Mothers With Hypothyroidism: Systematic Review

Introduction: Congenital hypothyroidism (CH) is one of the most common preventable causes of intellectual disability. A few studies have reported a higher prevalence of CH among neonates born to mothers with hypothyroidism but results are variable. Hence, we did a systematic review to understand the prevalence and need for second screening. Aims and Objectives: To determine the global prevalence of CH in neonates born to mothers with hypothyroidism and to analyze the need for second screening. Methods: The systematic review was performed per the PRISMA reporting guidelines. PubMed and Google Scholar database were searched in October 2023 and a total of 11 articles were included. Transient hyperthyrotropinemia was defined as thyrotropin (TSH) >10 mIU/L ≥14 days but normalization by 30 days of life without initiation of LT4 replacement whereas those received LT4 replacement were classified as congenital hypothyroidism (CH). CH patients in whom LT4 was stopped ≤3 years of age, TSH <40 mIU/L at initiation of LT4 treatment but further follow-up unavailable or author defined transient congenital hypothyroidism (TCH) were considered as TCH whereas others are considered as permanent CH. Results: A total of 4368 neonates of mothers with hypothyroidism were included from 11 studies. The pooled prevalence rates of total CH, permanent CH, transient CH and transient hyperthyrotropinemia were 1 in 161, 1 in 351, 1 in 320, and 1 in 325 respectively. Conclusion: This systematic review showed high prevalence of CH in neonates of maternal hypothyroidism. However, further studies are required for the implication of second screening.