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KID Description of Data Elements
The KID is set of longitudinal hospital inpatient databases included in the HCUP family. These databases are created by AHRQ through a Federal-State-Industry partnership.
BWT - Birth weight in grams
Documentation Sections:
General Notes
Uniform Values
State Specific Notes
General Notes

Birth weight (BWT) is coded in grams. No edit check comparing the birth weight to the diagnosis or procedure codes is performed.

Uniform Values
VariableDescriptionValueValue Description
BWTBirth weight in grams228-9143Grams
.AInvalid: Beginning with 1998 data, range check of 0.5 lbs (228 grams) to 20 lbs (9143 grams) was applied to the source data
State Specific Notes


In 1993, Colorado began collecting birth weight of newborns, but it was optional for hospitals to report this data to the hospital association.


Indiana provides the birth weight for newborn and neonates. Neonates are defined as children less than 29 days old.


Beginning in 2008, birthweight was available and used on the inpatient files.

Beginning in 2007, birthweight was 100% missing on Kentucky inpatient and outpatient files and thus was not retained on HCUP files

Kentucky hospitals provide the birth weight of the newborns in either pounds/ounces or grams. During HCUP processing birth weights coded in pounds/ounces are converted into grams.


For 2001, Maine does not collect information on birth weight directly. The information is extrapolated from the 5th digit of ICD-9-CM diagnosis codes 764-765 and provides only the midpoints of the weight ranges.


For 1990-1992, birth weight was reported by Maryland but was not processed as an HCUP variable. Beginning with 1993 discharges, birth weight is available in the HCUP Maryland data.

New Jersey

New Jersey documentation indicates that birth weight is reported for children under 29 days old. New Jersey restricts the values of birth weight to the range 100-9000 grams.


Internet Citation: HCUP KID Description of Data Elements. Healthcare Cost and Utilization Project (HCUP). September 2008. Agency for Healthcare Research and Quality, Rockville, MD.
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Last modified 9/17/08