Congenital hypothyroidism is a more common pediatric endocrine disorder and also most common preventable cause of mental retardation. Early diagnosis by measuring Thyroid hormones thyroxine (T4), Thyroid Stimulating Hormone (TSH) levels and prompt treatment is crucial in improving intellectual outcome and for growth of the baby. There are several perinatal factors which influence cord blood TSH, T4 values which has to be considered while interpreting the results. Umbilical cord blood samples were collected for assessment of TSH and T4 in 100 newborns. The influence of birth weight and gestational age on T4 & TSH levels was assessed. On comparing mean TSH and T4 levels among preterm and term infants, it was found that there was statistically significant difference in the mean TSH levels between term and preterm infants. Difference in mean T4 levels among low birth weight and normal birth weight infants was statistically significant. To conclude Birth weight & gestational age have influence on Cord blood TSH and T4 levels and a caution in their interpretation should be considered.