Figure 60-4 The glomerular filtration rate is markedly impaired at birth but develops rapidly during the first year of life. The ability of the kidney to handle large amounts of solutes and water is also limited during the first several months of life. These developmental changes have significant implications for drug excretion and fluid therapy, particularly during the first 4 weeks of life. Maturation of renal function may be delayed in sick neonates. (Data from McCrory WW: Developmental Nephrology. Cambridge, MA, Harvard University Press, 1972.)