Biomedical subjects

I Emanuel

Publications and source records attributed to I Emanuel.

15 recordsLinked to original sources

PubMed1992

The contrasting effects of parental birthweight and gestational age on the birthweight of offspring.

Investigations on intergenerational effects on birthweight have been carried out using the data of the 1958 British National Birthday Trust Fund cohort and its follow-up to 23 years, the National Child Development Study (NCDS-4), which included information on all births to cohort members by that age. This report is directed particularly at ascertaining the independent effect of parental gestational age on babies' birthweight. The two main findings are a direct association between parental and offspring birthweight (significant for both mothers and fathers after allowing for confounding factors), but an inverse association with parental gestational age (significant only for the mothers). It is postulated that at least part of this effect is mediated through the association between maternal fetal growth rate and their babies' birthweight; the faster the rate the shorter the gestational age for a given birthweight. It was not possible to ascertain what part genetic factors played in this relationship. Larger and more informative intergenerational studies are needed to further knowledge on this question.

Adult↗

PubMed1992

Intergenerational studies of human birthweight from the 1958 birth cohort. 1. Evidence for a multigenerational effect.

OBJECTIVE: To investigate possible multigenerational influences on birthweight. DESIGN: Data from the longitudinal study of one week's births in 1958 up to the age of 23 years, the British National Child Development Study, were utilized. These provide socio-biological information on the parents of the cohort, on the cohort members from birth onwards, and on the pregnancies and the birthweight of any babies born to the cohort members. MAIN OUTCOME MEASURE: The main outcome was the birthweight of babies born to the cohort members, for whom complete intergenerational data were available for 1638 firstborn. Multiple regression modelling was used to investigate any associations between their birthweight and characteristics of their parents and grandparents. RESULTS: Significant positive associations were found between babies' birthweight and parental birthweight but not gestational age. For the babies born to female cohort members additional findings included associations between their birthweight and the height of the maternal grandmother and the social class of the maternal grandfather, even after adjustment for such strong predictors of birthweight as maternal weight, smoking habit in pregnancy and baby's sex and birth order. CONCLUSION: These results thus offer support for a multigenerational influence on birthweight passed through the maternal line.

Birth Weight↗

PubMed1992

Intergenerational studies of human birthweight from the 1958 birth cohort. II. Do parents who were twins have babies as heavy as those born to singletons?

OBJECTIVE: To ascertain whether maternal twinning influences the previously described association between the birthweight of singleton mothers and their infants. DESIGN AND SUBJECTS: The association between the birthweight of singleton parents and their offspring and that between twin parents and their offspring was compared using data from the 23-year-old sample of the 1958 British national birth cohort. The numbers available for full comparison were 1027 female and 611 male singleton cohort members, and 26 female and 17 male twin cohort members and their first singleton livebirths. RESULTS: Of the mothers who had been twins, half had been of low birthweight, and overall their mean weight was 700 g less than that of their singleton counterparts. Nevertheless, the mean birthweight of babies of twin mothers was 133 g, and of twin fathers 94 g, greater than of babies of corresponding singletons. For female, but not male, parents this difference persisted after adjustment for confounding variables. CONCLUSIONS: We suggest two possible reasons for the difference between the weight of babies of twin and singleton mothers. Firstly, the growth of twins becomes retarded late in pregnancy, possibly after a period critical in determining long-term reproductive effects. Secondly, the twin survivors were of higher birthweight than the original twin cohort, whilst the singleton survivors were more representative of all singleton births, thus introducing a possible bias.

Birth Weight↗

PubMed1991

Comparison of linear and exponential multivariate models for explaining national infant and child mortality.

Product form multivariate regression models (multiplicative exponential) were developed with infant and child mortality as outcomes, and national economic, health, nutrition, education, and demographic statistics as predictor variables. The models were applied to data from 129 countries, resulting in R-square values for the product form models of infants and child mortality of 0.77 and 0.80. For comparison purposes, more conventional sum form models (additive linear) were also estimated, and yielded R-square values (0.22, 0.29) markedly lower than the product form models. The product form models also had a much more uniform distribution of residuals and provided improved model fit across the different categories of nations. An inherent advantage to the product form models is that they did not predict negative mortality rates, in contrast to the sum form models which did predict negative mortalities for some of the more developed nations. Using a product form model, the correlation between physicians per capita and infant mortality was shown to be negative rather than positive--thus correcting for an anomaly seen in previous studies which showed a positive correlation between physicians per capita and infant mortality.

Child↗

PubMed1991

Gestational duration and birthweight in white, black and mixed-race babies.

Using the 1983 United States population of single live births, birthweight and gestational duration were compared for babies of these different parental racial groups: both parents White, mother White-father Black, mother Black-father White, both parents Black. The four groups differed significantly with respect to the usual sociodemographic variables. Mean birthweight and mean gestational duration decreased in that order from the White-White reference group, and conversely there were increasing trends for low birthweight and preterm delivery. Adjustment for the usual sociodemographic variables did not alter these trends appreciably. Group differences were more strongly related to the mother's race than to the father's, and the trends were related to the mother's race. Because the father's race was significant, genetic factors are probably of some importance. The evidence from this study, together with the often-demonstrated relationships between low birthweight and preterm delivery with sociodemographic variables, and the short-term downward secular trends in low birthweight, support the concept that non-genetic maternal factors are more important for these abnormal outcomes. But because neither the usually utilised sociodemographic variables nor genetic factors seem to explain much of the group differences, new approaches are necessary to understand why, irrespective of ethnic group, some women are at excess risk for suboptimal birth outcome.

Adolescent↗

PubMed1989

Interannual variation of the incidence of Haemophilus influenzae type b meningitis.

We conducted a population-based retrospective cohort study to define the annual age-specific incidence of Haemophilus influenzae type b meningitis for birth to 5-year-old residents of King County, Washington, from January 1977 through December 1986. We found naturally occurring wide interannual variations in incidence. The standard deviations of the age-specific incidence during the eight years before the introduction of H influenzae vaccine varied from 26% to 115% of the mean. If short-term changes in incidence were used to assess the efficacy of an H influenzae vaccine (which is less than 100% efficacious and not administered to all susceptible children), the conclusions could be erroneous. To avoid this bias, long-term cohort studies, case/control studies using concurrent controls, or large clinical trials are better choices. We found no significant change in overall incidence during the ten-year study period.

Age Factors↗

PubMed1989

Poor birth outcomes of American black women: an alternative explanation.

The dramatic excess of low birthweight and infant deaths among black babies compared to whites cannot be completely explained by differences either in sociodemographic factors or in prenatal care patterns. It is suggested that part of the explanation resides in characteristics of the mothers' own intrauterine and childhood environment which interfere with their optimal growth and development and become manifest later in suboptimal reproductive outcome. Conditions in the adult environment under which pregnancies occur also appear to interfere with fetal development. This evidence points to the need for programs to care for children as they grow and develop and for women before and during their pregnancies. Research should be encouraged which may help to elucidate the biological mechanisms by which intrauterine, childhood and adult environments of one generation translate into health hazards for the next generation.

Black or African American↗

PubMed1986