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

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

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

New York restricts the values of birth weight. Values less than 100 grams are set to 100; values greater than 9000 grams are set to 9000 grams.

Beginning with the 2008 data, birth weight (BWT) is rounded down to the nearest 100 grams on all discharges for AIDS/HIV newborn patients. New York identifies AIDS/HIV records by ICD-9-CM diagnosis code or DRG:

• An admitting, principal, or secondary diagnosis of "042" "043" "044" "7958" "27910", "27919", "2793", "1363", "79571", "07951", "07952", "07953", "V017" or "V08".
• A DRG of 488 through 490 or 700 through 716.

For 2005 - 2007 data, birth weight (BWT) is rounded down to the nearest 100 grams on AIDS/HIV newborn discharges. New York identifies AIDS/HIV records by ICD-9-CM diagnosis code or DRG:

• An admitting, principal, or secondary diagnosis of "042" "043" "044" "7958" "27910", "27919", "2793", "1363", "79571", "07951", "07952", "07953", "V017" or "V08".
• A DRG of 488 through 490 or 700 through 716.

For the 1998 - 2004 data, New York rounded down the birth weight to the nearest 100 grams on AIDS/HIV newborn discharges. New York identifies AIDS/HIV records by ICD-9-CM diagnosis code or DRG:

• An admitting, principal, or secondary diagnosis of "042" "043" "044" "7958" "27910", "27919", "2793", "1363", "79571", "07951", "07952", "07953" or "V08".
• A DRG of 488 "HIV with Extensive Operating Room Procedure", 489 "HIV with Major related condition", or 490 "HIV with or without Other Related Condition".

Please note that the admitting diagnosis is not retained in the HCUP databases.