The UK DNA banking network: a "fair access" biobank.

The UK DNA Banking Network (UDBN) is a secondary biobank: it aggregates and manages resources (samples and data) originated by others. The network comprises, on the one hand, investigator groups led by clinicians each with a distinct disease specialism and, on the other hand, a research infrastructure to manage samples and data. The infrastructure addresses the problem of providing secure quality-assured accrual, storage, replenishment and distribution capacities for samples and of facilitating access to DNA aliquots and data for new peer-reviewed studies in genetic epidemiology.

Paradox found (again): infant mortality among the Mexican-origin population in the United States.

Recent research suggests that the favorable mortality outcomes for the Mexican immigrant population in the United States may largely be attributable to selective out-migration among Mexican immigrants, resulting in artificially low recorded death rates for the Mexican-origin population. In this paper we calculate detailed age-specific infant mortality rates by maternal race/ethnicity and nativity for two important reasons: (1) it is extremely unlikely that women of Mexican origin would migrate to Mexico with newborn babies, especially if the infants were only afew hours or afew days old; and (2) more than 50% of all infant deaths in the United States occur during the first week of life, when the chances of out-migration are very small. We use concatenated data from the U.

Demographic models of birth outcomes and infant mortality: an alternative measurement approach.

Most demographic studies use 2,500 grams of birth weight and 37 weeks of gestation as cutpoints for evaluating the effects of adverse birth outcomes on infant mortality. We propose an alternative strategy, which relies on continuous measures of birth outcomes, identifies an optimal combination of birth weight and gestational age for infant survival, and estimates the effects of adverse birth outcomes in terms of their departure from this "optimal point." We illustrate the advantages of this approach by estimating a logistic model using data from the 1989-1991 NCHS linked birth/infant death files.

Birth outcome, not pregnancy process: reply to van der Veen.

In a recent article (Frisbie, Forbes, and Pullum 1996) we documented racial/ethnic differences in birth outcomes according to a more fine-grained classification than has typically been employed in the demographic literature. In his commentary, van der Veen focuses on the measurement of one of the dimensions of that classification, maturity of the infant, as proxied by the fetal growth ratio. The crux of the critique is easily seen in van der Veen's statement that "all of my disagreements with Frisbie et al.

Racial and ethnic differences in determinants of intrauterine growth retardation and other compromised birth outcomes.

Objectives: This study examined the extent of variation by race/ethnicity in the prevalence of adverse birth outcomes, whether differentials persisted after other risk factors were controlled for, and whether the direction and magnitude of relationships differed by type of outcome.

Methods: A revised system of measurement was used to estimate multinomial logistic models in a large, nationally representative US data set.

Results: Considerable racial/ethnic variation was found across birth outcome categories; differences persisted in the adjusted parameter estimates; and the effects of other risk factors on birth outcomes were similar as to direction, but varied somewhat in magnitude.