Please do not be worried about the lowered TSH
levels till your baby's dose is settled by the doctor. Do not check TSH this frequently. Main idea of treating your infant with thyroid hormone is to avoid future problems of body/ brain development etc. Hence at this stage follow the doctor's advice as and how he/ she advises you on your baby's doses. Give importance to developmental milestones once the baby is on medication. I hope you understand. Take care.
One important thing: when the newborn has hypothyroidism
he/ she must be checked for missing thyroid tissue or ectopic (developed at abnormal location other than normal midline neck position) thyroid tissue from an Endocrinologist
. This helps in future prognosis.