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The term "neonate" is defined as any infant up to the age of twenty-eight days (i.e., through 27 days, 23 hours, and 59 minutes from the moment of birth). The neonatal period represents the end stage of newborn development that spans the entire time before birth (prenatal), starting with the fertilized embryo. Early embryonic development is described in stages that correspond to time periods during which human embryos develop specific morphological characteristics. Stage one begins at fertilization, spanning the first fifty-six days and ending as stage twenty-three. Next, at the fifty-seventh day, the "fetal period" begins; it ends with the completion of delivery outside of the mother. The neonate is unique in his/her vulnerability to the extrauterine environment resulting in higher risk for mortality and morbidity compared to later in infancy. Precise terminology is important for accurate interpretation and comparisons of databases related to newborn concerns.


American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. Guidelines for Perinatal Care, 4th edition. Washington, DC: American Academy of Pediatrics, 1997.

Moore, Keith, and T. V. N. Persaud. The Developing Human, Clinically Oriented Embryology. Philadelphia: W. B. Saunders, 1998.

Carol A. Miller

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Social Issues ReferenceChild Development Reference - Vol 6