the dosage of thyroxine
is usually increased by 30-50%; the intention is to maintain a TSH level of 2.5mIU/l in early pregnancy and 3mIU/l in late pregnancy. Preterm birth, growth retardation, neonatal respiratory distress
are some of the complications that can happen when the defect is uncorrected. Please follow your doctor's instructions and maintain a euthyroid state to avoid any complications. Brain development is not affected by hypothyroidism
. Hope your query is clarified. Wish you safe motherhood.