Congenital hypothyroidism (CH) is the commonest cause of preventable mental retardation. The crucial point to remember when screening for CH is the neonatal surge of TSH and T4. The TSH surge starts 30 min after birth (T4 some hours later), is most marked for the next 24 hours, but may persist for 48 to 72 hours. Thus, cord blood is largely spared of the neonatal surge. Cord blood TSH values are affected by certain conditions in which a baby is born. These risk factors are babies requiring resuscitation measures, cesarian section done to deliver the newborn suffering from fetal distress ; premature low birth weight babies.