title: Are very low birthweight births among American Indians and Alaska Natives underregistered?
abstract: BACKGROUND
  International infant mortality rates vary widely. This variation has been attributed to many factors, including differential reporting. In the US, American Indians and Alaska Natives (AI/AN), who generally have low socioeconomic status, have a low neonatal mortality rate. One possible explanation is underregistration of very low birthweight (VLBW, < 1,500 g) births. We hypothesized that underregistration may occur disproportionately among AI/AN residing on or near reservations (areas controlled by an American Indian group). We estimated infant mortality in these areas.
  
  
  METHODS
  Linked birth-infant death files for 1989-1991 were used to compare VLBW and neonatal mortality among AI/AN infants in counties with reservations with those in non-reservation counties. The VLBW rates for non-reservation counties were applied to the reservation risk distribution to calculate directly adjusted VLBW and neonatal mortality rates for reservation counties. This method assumes that greater registration in non-reservation counties yields a more accurate estimate of the relationship between risk factors and outcomes.
  
  
  RESULTS
  Despite a higher prevalence in reservation counties of risk factors, the reported VLBW rate was 0.84% in reservation and 1.17% in non-reservation counties. The neonatal mortality rate was 5.4 per 1,000 in reservation counties and 6.0 in non-reservation counties. Direct adjustment yielded a VLBW rate of 1.28% (95% CI: 1.14-1.39) and a neonatal mortality rate of 6.7-9.8 per 1,000 in reservation counties.
  
  
  CONCLUSIONS
  Reported neonatal mortality among AI/AN may understate the true rate due to underregistration of VLBW births. Direct adjustment may be useful in estimating infant mortality rates for populations with incomplete vital registration.
authors.affiliation: National Center for Health Statistics, Hyattsville, MD 20782, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Heck
authors.forename: K C
authors.initials: KC
authors.lastname: Schoendorf
authors.forename: J
authors.initials: J
authors.lastname: Parker
mesh_terms: D017677:Age Distribution; D000413:Alaska / Q000453:epidemiology; D004522:Educational Status; D005313:Fetal Death / Q000453:epidemiology; D006801:Humans; D007198:Indians, North American / Q000706:statistics & numerical data*; D007226:Infant Mortality; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D004930:Inuit / Q000706:statistics & numerical data*; D015995:Prevalence; D012042:Registries / Q000706:statistics & numerical data*; D012307:Risk Factors; D015996:Survival Rate; D014481:United States / Q000453:epidemiology