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Central Distributor SID: Description of Data Elements
This section describes how HCUP data elements are coded, restrictions on their use, their uniform values, and State-specific coding practices.
MOMNUM_R - Mother's number (re-identified)
Documentation Sections:
General Notes
Uniform Values
State Specific Notes
General Notes

MOMNUM_R is specific to the mother of the baby in a particular hospital. MOMNUM_R does not allow linkage of persons across institutions.

Because of a change in the algorithm for creating person identifiers, mothers cannot be tracked from before 2003 to after 2003. In HCUP data prior to 2003, a synthetic mother's medical record number (MOMNUM_S), created using fixed-key encryption, was available. Starting in data year 2003, a reidentification number (MOMNUM_R) was used. MOMNUM_R includes an arbitrarily chosen, identifying number that is unique to the mother's medical record identifier provided to HCUP.

Uniform Values
VariableDescriptionValueValue Description
MOMNUM_RMother's number (re-identified)9(n)Mother's number
State Specific Notes


MOMNUM_R contains the medical record number of the mother for newborn birth and infant identification. The mother's record will contain her medical record number in the HCUP variable MRN_R. Michigan documentation indicates that use of this field is optional. Not all the hospitals that have obstetrics units provide the data.

New Jersey

Beginning in 2014 the source values changed; therefore, they are not consistent with data from previous years.

MOMNUM_R contains the synthetic medical record number of the mother on newborn discharges. The mother's record will contain her synthetic medical record number in the HCUP variable MRN_R.

Prior to the 2010 data year, mothers' medical record numbers were encrypted using a specific encryption routine that is different from the routine used to encrypt medical record numbers. Because of the use of different encryption routines for these two fields, values in the MOMNUM_R field do not match the values in MRN_R field.


Internet Citation: HCUP Central Distributor SID Description of Data Elements - All States. Healthcare Cost and Utilization Project (HCUP). August 2008. Agency for Healthcare Research and Quality, Rockville, MD.
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Last modified 8/12/08