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Serum free T4 levels in cord blood, and at 7, 14 and 28 days of life in neonates of 23-27, 28-30, 31-34, and 37+ weeks gestation. With permission from Williams FL, Simpson J, Delahunty C, et al. Developmental trends in cord and postpartum serum thyroid hormones in preterm infants. J Clin Endocrinol Metab 2004; 89:5314-5320 (9).
