Descriptive analyses of birthweight for single live births in the United States during 1974, using birth certificate information, show that several factors are associated with a high incidence of low birthweight babies. Multivariate analyses were performed to determine correlates of low birthweight. When other factors are held constant, race not white, previous reproductive loss, short interpregnancy interval, outof-wedlock birth, no prenatal care, and maternal age Recent studies of pregnancy outcome have shown a progressive decline of perinatal and infant mortality in all risk categories, including mortality for small preterm infants.' The decline has come at a time of change in many aspects of maternal and infant care: associated factors include improved perinatal services available to both mother and baby, improved care or prevention of specific diseases, and an increased availability of means for spacing or preventing pregnancies.In our study of birth certificate information to evaluate specific factors which increase the risk of a poor pregnancy outcome, we have followed the suggestion of Lewis, et al.,2 and use birthweight distribution as an indicator of pregnancy outcome. Although infant mortality rates remain the primary indicator, low birthweight is also an indicator of considerable interest. Low birthweight is associated with increased perinatal and infant mortality and morbidity, including adverse sequelae such as mental retardation and learning disabilities.Many previous studies have shown that birthweight, in- The study from which the present report has been drawn'4 comprised an examination of United States birth registration data for single live births in 1974. For each race it related the proportion of births which were low birthweight (less than 2501 grams) to risk factors ascertainable from birth certificates. We summarize here the principal findings of that study and report the results of multivariate analyses which examine the risk of having a low birthweight baby by race, maternal age, wedlock status, prenatal care, and maternal education for primigravida, and by these factors and birth order, reproductive history, and interpregnancy interval for multigravida.

as a standard, was photographically enlarged to an arbitrary length of 10 cm, and the other patterns were adjusted to equivalent migration velocities by reference to their T. dicoccum homologs.The tetraploid pattern invariably comprised two different series of protein fractions, a fast-moving one of broad, widely spaced bands beginning at -10.0 cm and a slow-moving one of narrow, closely spaced bands beginning at -4.0 cm. Owing partly to the degree of band separation obtained, the slower series provided inconclusive evidence on which to categorize the Triticum accessions, but in the fast series the tetraploids of the Emmer and Timopheevi groups were readily distinguishable.The Syrio-Palestinian race of T. dicoccoides appears to be the progenitor of the Emmer group. On the basis of regular chromosome pairing in the F1 hybrids among these tetraploids, there is general agreement that they are all of the genome constitution AABB. Their B genome is thought to have been derived from Aegilops speltoides Tauch.Like T. dicoccum (Fig. 1), all species in the Emmer group, including the Syrio-Palestinian race of the wild tetraploid, gave a pattern with eight bands in the fast series with centers at -9.7, -9.0, -8.1, -7.4, -6.9, -6.0, -5.0, and -4.3 cm. Frequently the band at -8.1 and sometimes that at -6.9 were double. The species were essentially identical also with respect to the density of the individual bands. That at -9.0 was the densest, and those at -6.0 and -5.0 were the faintest, except in T. carthlicum and T. turanicum, where the band at -5.0 sometimes was nearly as dense as that at 9.0.The Transcaucasian race of T. dicoccoides is apparently the progenitor of the Timopheevi group. Hybrids among these tetraploids also exhibit for the most part regular chromosome pairing, but F1 hybrids between members of the Timopheevi and Emmer groups are highly sterile (5), owing to failure of pairing among chromosomes presumably of the second genome (10). For this reason, the Timopheevi tetraploids were originally assigned the presently controversial genome formula AAGG.Like T. timopheevi, all species of as a standard, was photographically enlarged to an arbitrary length of 10 cm, and the other patterns were adjusted to equivalent migration velocities by reference to their T. dicoccum homologs. The tetraploid pattern invariably comprised two different series of protein fractions, a fast-moving one of broad, widely spaced bands beginning at -10.0 cm and a slow-moving one of narrow, closely spaced bands beginning at -4.0 cm. Owing partly to the degree of band separation obtained, the slower series provided inconclusive evidence on which to categorize the Triticum accessions, but in the fast series the tetraploids of the Emmer and Timopheevi groups were readily distinguishable.The Syrio-Palestinian race of T. dicoccoides appears to be the progenitor of the Emmer group. On the basis of regular chromosome pairing in the F1 hybrids among these tetraploids, there is general agreement that they are all of the genome constitution AABB. The...

Regression analysis of daily mortality in Los Angeles County shows that there is a significant association between community carbon monoxide concentrations and mortality. Cyclic variation and maximum temperature were the main contributors. No association was demonstrated between oxidant and mortality.

An analysis of 1983 data from California birth certificates, and from the California Birth Defects Monitoring Program case registry, showed that there is a bias in reporting of congenital malformations on the birth certificate. Hospitals with many births erroneously report lower malformation rates than do hospitals with few births. The bias is partly due to the source of information; larger hospitals are more likely to get their information about malformations from the obstetrician than from the pediatrician. Since malformation data recorded on the birth certificate is both incomplete and biased, at present it is advisable to use these data for epidemiologic analyses with great caution.

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