New data items RIDAGEEX and RIDEXPRG have been added to the Demographics 
files for 1999-2000 and 2001-2002, and existing RIDAGEMN has been expanded 
to include data for survey participants up to 85 years of age in these 
files.  These items have already been released as part of the 2003-2004 
Demo file.  Further details can be found in the data documentation; 
relevant text from the 2001-2002 Demographics documentation file is 
excerpted below for your convenience:

“RIDAGEMN is age in months at household screening, provided only for those 
under 85 years of age (RIDAGEYR<85).  If the exact date of birth is not 
provided by the sample person, then the age in months is calculated based 
on the imputed age at screener to allow the sample person to proceed with 
the questionnaire and examination.”

“RIDAGEEX is age in months at MEC examination, provided only for those 
under 85 years of age at household screening (RIDAGEYR<85).  Some 
respondents have missing values for RIDAGEEX because their exact date of 
birth was not available.  RIDAGEEX was not  calculated for individuals with 
an imputed age at screener value.”

“PREGNANCY STATUS: Pregnancy status at the time of examination (RIDEXPRG) 
is reported for females 8-59 years of age. The information used to code 
RIDEXPRG values included urine pregnancy test results and self-reported 
pregnancy status. Urine pregnancy tests were performed prior to the dual 
energy x-ray absorptiometry (DXA) exam; menstruating females 8-11 years of 
age and all females 12 years and over received a urine pregnancy test.  
Persons who reported they were pregnant at the time of exam were assumed to 
be pregnant; if the urine test was negative, but the subject reported they 
were pregnant, the status was still coded as pregnant at exam (RIDEXPRG=1). 
If the urine pregnancy results were negative and the respondent said they 
were not pregnant, the respondent was coded not pregnant at examination 
(RIDEXPRG=2). Persons who were only interviewed have an RIDEXPRG value = 3 
(could not be determined).  

Note: The pregnancy recode variable which was previously released with 
NHANES 1999-2000 and NHANES 2001-2002 data was called RIDPREG.  RIDPREG was 
created to allow analysts to exclude pregnant women from analyses; this 
determination was based on the most comprehensive information available at 
the time of data release.  RIDPREG was a more conservative indicator of 
pregnancy status, and was derived using several sources of information.  For 
subjects who were only interviewed, pregnancy status at the time of survey 
screening, and menstrual status were used to determine possible pregnancy 
status.  For examined individuals, if an individual indicated that they were 
pregnant during the reproductive health questionnaire (RHQ), or reported 
they were pregnant in the shared exclusion questions (SEQ), or had a 
positive urine pregnancy test, these individuals were determined to be 
pregnant. If an individual was screened as pregnant and had other 
information which supported the information in the reproductive health 
uestionnaire (RHQ), they were determined to be pregnant.  If an individual 
indicated that they were not pregnant and also had a negative urine pregnancy 
test, they were determined to not be pregnant. 

Analysts may find that a variable indicating pregnancy status at the time of 
exam (RIDEXPRG) is a more useful analytic variable rather than the more 
conservative RIDPREG.  Approximately 20-25 individuals per 2-year cycle 
during NHANES 1999-2000 and NHANES 2001-2002 could have different pregnancy 
status values using the RIDEXPRG and RIDPREG algorithms.”