Low Birth Weight / Prematurity
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The low birth weight (LBW)infant is a baby who is born smaller and lighter than a normal full term infant. A LBW infant is a baby with a birth weight under 2500 grams (5 pounds 8 ounces). A very low birth weight infant (VLBW) is a child born with a birth weight under 1500 grams (3 pounds 5 ounces). The most frequent cause of low birth weight is prematurity, i.e. being born three weeks or more before the due date. A normal, full-term pregnancy lasts 37 to 42 weeks; the due date is calculated at 40 weeks from the last menstrual period. Full term infants may also be born LBW, for example because of inadequate nutrition in utero or a genetic disorder.
LBW infants may have health problems during the early days or months of life due to the immaturity of their organ systems, such as their lungs and gastrointestinal tract. LBW infants are also at a greater risk than normal full term newborns for neurologic problems leading to long-term disability, although most LBW infants do very well. The smaller an infant is at birth, the greater the risk of health and developmental complications. As experience and expertise in the care of LBW infants has increased many of the 'larger' LBW infants, who in the past had complications, are surviving without problems. While the LBW infant still may have a problem, close monitoring is now primarily directed to children born VLBW.
Approximately 309,000 LWB infants are born annually in the United States. This represents 7.6% of total US births in 2000. (Pediatrics, 2001; 108 (6): 1241-1255)
Primary Reviewer LBW/ Prematurity Section
Katherine TeKolste, MD
Sue Wendel, OT
Kate Orville, MPH
Change in prevalence of chronic conditions between childhood and adolescence among extremely low-birth-weight children. Hack M, Schluchter M, et al. JAMA. 2011;306(4):394-401. doi: 10.1001/jama.2011.1025. Abstract.
Extremely LBW children have high rates of chronic conditions
during childhood. This article examines changes in the rates of chronic conditions between the ages of 8 and 14 years among ELBW children compared with
normal-birth-weight (NBW) controls born from 1992 through 1995 in Cleveland, OH. The overall rates
of chronic conditions did not change significantly between the ages of 8
and 14 years among ELBW children
(75% at age 8 years vs 74% at age 14 years) or NBW
controls (37% at age 8 years vs 47% at age 14 years). Differences in rates of asthma between ELBW and NBW children were no longer significant at the age of 14 years due to increased rates in normal birthweight controls, while the ELBW group rate remained stable. Rates of obesity in the ELBW children increased from 12% at age 8 years to 19% at age 14 years.
Meta-Analysis of Neurobehavioral Outcomes in Very Preterm and/or Very Low Birth Weight Children. Aarnouodse-Moens CSH et al. Pediatrics. 2009;124:717-728.
Hospital Discharge of the High-Risk Neonate - AAP Policy Statement, November 2008 LINK
Update of the 1998 Guidelines.
NICU Micropreemies: How do they fare?
Blackman J. Contemporary Pediatrics. Feb 2007. Information on the neurodevelopmental outcomes of infants less than 800 grams birthweight. LINK
Preterm Birth: Causes, Consequences, and Prevention
The Institute of Medicine convened a committee to
assess the current state of the science on the causes and broad
consequences of preterm birth. An overview of the committee's
recommendations is presented in Preterm Birth: Causes, Consequences,
and Prevention. Topics include measurement, causes of preterm birth,
diagnosis and treatment of preterm labor, consequences of preterm
birth, and research and policy. The prepublication version of the full
committee report is available at
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