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Large for gestational age newborn

George T Mandy, MD
Section Editor
Leonard E Weisman, MD
Deputy Editor
Melanie S Kim, MD


Infants who are born large for gestational age (LGA), especially full-term or post-term infants, are at risk for perinatal morbidity and potentially long-term metabolic complications.

The pathogenesis, epidemiology, risk factors, complications, and management of infants born LGA will be reviewed here.


In general, LGA is defined as a birth weight (BW) greater than the 90th percentile for age. However, it has been suggested that the definition be restricted to infants with BW greater than the 97th percentile (2 standard deviations above the mean), as this more accurately describes infants who are at greatest risk for perinatal morbidity and mortality [1,2]. Using a national reference based on single live births in the United States, infants born at 40 weeks gestation at the 90th percentile had BW greater than 4000 g and those at the 97th percentile greater than 4400 g [3].

Macrosomia refers to excessive intrauterine growth beyond a specific threshold regardless of gestational age (GA). This condition usually is defined as a BW greater than 4000 or 4500 g. The American College of Obstetricians and Gynecologists (ACOG) supports use of the 4500 g threshold for diagnosis of macrosomia because morbidity increases sharply beyond this weight.

A grading system for macrosomia has been proposed based on BW (see "Fetal macrosomia", section on 'Definition'):

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Literature review current through: Nov 2017. | This topic last updated: Mar 22, 2016.
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