Background: The clinical manifestations of congenital hypothyroidism (CH) are often subtle and not evident at birthand so many newborn infants remain undiagnosed in the absence of routine newborn screening. This delay in the diagnosis leads to the most severe outcome of CH which is mental retardation. CH isone of the most common preventable causes of mental retardation. Aim: To determine the prevalence of CH in preterm and term neonatesborn to hypothyroid mothers, assessment of their physical parameters at birth; growth and neurodevelopment till 6 months of age. Methods: The study was conducted at K.M. Medical College & Hospital, Mathura as a prospective observational study from April 2022 to September 2023after obtaining clearance from institutional ethical committee. Fiftyconsecutive pregnant hypothyroid mothers suffering from subclinical and overt hypothyroidism were enrolled over a period of 12 months. They were started on levothyroxine andgood compliance was ensured. Results: Out of 50 babies born, 45babies were included in the study while 5 were excluded as they required admission in neonatal intensive care unit. None suffered from CH requiring treatment. Only 4 babies have TSH > 20 mIU/L (<40 mIU/L) with normal fT4 at 72 hours of life but, later it normalized at 2 weeks of life. There was nostatistically significant differencein the anthropometric measurements between preterm and term babies. All babies were followed up to 6 months of age and assessedfor their neurodevelopment which was found to be normal. Conclusions: Early diagnosis of hypothyroidism in pregnancy and its timely treatment prevents CH in neonates and promotes their adequate growth and neurodevelopment. Also, there should be screening of newborns for CH as they will have maximum benefit from early initiation of treatment.