title: Customized birth weight for gestational age standards: Perinatal mortality patterns are consistent with separate standards for males and females but not for blacks and whites.
abstract: BACKGROUND: Some currently available birth weight for gestational age standards are customized but others are not. We carried out a study to provide empirical justification for customizing such standards by sex and for whites and blacks in the United States. METHODS: We studied all male and female singleton live births and stillbirths (22 or more weeks of gestation; 500 g birth weight or over) in the United States in 1997 and 1998. White and black singleton live births and stillbirths were also examined. Qualitative congruence between gestational age-specific growth restriction and perinatal mortality rates was used as the criterion for identifying the preferred standard. RESULTS: The fetuses at risk approach showed that males had higher perinatal mortality rates at all gestational ages compared with females. Gestational age-specific growth restriction rates based on a sex-specific standard were qualitatively consistent with gestational age-specific perinatal mortality rates among males and females. However, growth restriction patterns among males and females based on a unisex standard could not be reconciled with perinatal mortality patterns. Use of a single standard for whites and blacks resulted in gestational age-specific growth restriction rates that were qualitatively congruent with patterns of perinatal mortality, while use of separate race-specific standards led to growth restriction patterns that were incompatible with patterns of perinatal mortality. CONCLUSION: Qualitative congruence between growth restriction and perinatal mortality patterns provides an outcome-based justification for sex-specific birth weight for gestational age standards but not for the available race-specific standards for blacks and whites in the United States.
authors.affiliation: Perinatal Epidemiology Research Unit, Departments of Obstetrics and Gynaecology and of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada. ksjoseph@dal.ca.
authors.forename: K S
authors.initials: KS
authors.lastname: Joseph
authors.forename: Russell
authors.initials: R
authors.lastname: Wilkins
authors.forename: Linda
authors.initials: L
authors.lastname: Dodds
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Allen
authors.forename: Arne
authors.initials: A
authors.lastname: Ohlsson
authors.forename: Sylvie
authors.initials: S
authors.lastname: Marcoux
authors.forename: Robert
authors.initials: R
authors.lastname: Liston
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