Trends in perinatal characteristics in South Australia, 1981 to 1994, by place of residence of mother

Socio-economic differentials in the health-related quality of life of Australian children: results of a national study

OBJECTIVE

To examine differences in health-related quality of life (HRQL) of children living in different socio-economic contexts in Australia.

METHODS

Parental reports describing the HRQL and socio-economic status of a random national sample of 3,597 school-age children were obtained using the Child Health Questionnaire (CHQ) and a standardised socio-economic interview. Response rate was 70%.

RESULTS

Children in families of higher income, whose parents had more years of schooling and were employed and children who lived in two-parent, original families had significantly higher HRQL across a range of domains assessed by the CHQ.

CONCLUSION

Children from lower socio-economic backgrounds in Australia have a significantly more negative experience of health and wellness. Such differences may well increase unless deliberate political attention is given to addressing the widening differences in relative wealth in Australia.

Placental restriction alters circulating thyroid hormone in the young lamb postnatally

Intrauterine growth restriction (IUGR) is associated with accelerated growth and increased adiposity in early life due to unknown mechanisms, which could include increased thyroid hormone (TH) action. We hypothesized that placental restriction (PR) of fetal growth would increase circulating TH concentrations and alter their response to fasting, and that these would relate to growth and body composition in the young lamb. PR reduced size at birth, increased fractional growth rates (FGRs) of soft and skeletal tissues up to 30 days of age, and slowed the ontogenic decrease in plasma total T3 and plasma total T3/T4. PR did not alter the abundance of plasma THs after short-term fasting. In general, plasma total T3 and total T3/T4 ratio correlated negatively, whereas plasma total T4 correlated positively with size at birth. Absolute growth rates of weight and crown-rump length correlated positively with plasma total T3 and total T4 between days 15 and 35. Current FGRs for weight and metatarsal length correlated positively with plasma total T3 between days 20 and 35. In conclusion, PR and small size at birth reduce plasma total T4 and increase plasma total T3 postnatally, whereas catch-up growth relates to increased abundance of the more bioactive forms of TH. Finally, greater soft tissue growth occurs in PR compared with control lambs at the same circulating TH concentrations. This suggests that PR and small size at birth may increase activation of T4 to T3 and sensitivity of soft tissues to TH, which may contribute to catch-up growth following IUGR.

Nutrition before birth, programming and the perpetuation of social inequalities in health

The need to explain social inequalities in health has led to the theory that chronic disease is due, in part, to a legacy of adverse experiences in early life. Epidemiological studies show consistently that individuals who are small at birth have an increased risk of cardiovascular disease in adulthood. There is growing consensus that this association reflects a causal relationship and is not simply the product of bias or confounding. The concept of programming is invoked as the biological mechanism; birth size is thus a proxy for fetal programming. Recent findings suggest that fetal programming interacts with the post-birth environment. The adverse exposures that are thought to underlie and potentiate programming cluster in socially patterned ways, thus creating substantial inequalities in health. Experiments in animals demonstrate that nutritional interventions before or during pregnancy can produce programming phenomena in the offspring, sometimes without an impact on birth size. However, the extent to which maternal nutrition contributes to programming in contemporary developed countries is uncertain.

The Matthew effect: infant mortality in Canada and internationally

OBJECTIVE

To examine whether the magnitude of improvement in the health status of a population over time is dependent on the previous health status of that population.

DESIGN AND SETTING

A study of infant mortality rates in Canada's 12 provinces and territories between the periods 1961-1965 and 1991-1995, and of infant mortality rates in 133 countries between 1960 and 1995.

MAIN OUTCOME MEASURES

Spearman's rank correlations, relative risks, and risk differences to measure the relationship between infant mortality in the 1960s and changes in infant mortality between the 1960s and 1990s.

RESULTS

In Canada, regional rankings based on infant mortality rates in 1961-1965 were strongly correlated (inversely) with rankings based on the percent change in infant mortality between 1961-1965 and 1991-1995 (correlation coefficient = -.85). In contrast, internationally, rankings based on infant mortality rates in 133 countries in 1960 were positively correlated with percent change between 1960 and 1995 (correlation coefficient =.56). Regional differences in infant mortality rates, measured using relative risks, declined in Canada (highest relative risk: 4.2, compared with Ontario in the 1960s; highest relative risk: 2.2, compared with Ontario in the 1990s) but increased globally (highest relative risk: 5.0, compared with industrialized countries in 1960; highest relative risk: 15.1, compared with industrialized countries in 1995).

CONCLUSIONS

Canadian regions with higher infant mortality rates in 1961-1965 achieved larger improvements compared with regions with initially lower infant mortality rates. The pattern observed within Canada is unlike the pattern observed internationally.

The urban and rural divide for women giving birth in NSW, 1990-1997

OBJECTIVE

To examine trends in the pregnancy profile and outcomes of urban and rural women.

METHODS

Data were obtained from the NSW Midwives Data Collection on births in NSW, 1990-1997. Associations between place of residence (urban/rural) and maternal factors and pregnancy outcomes were examined, including changes over time.

RESULTS

From 1990 to 1997 there were 685,631 confinements in NSW and these mothers resided as follows: 76% metropolitan, 5% large rural centres, 8% small rural centres, 11% other rural areas and 1% remote areas. Rural mothers were more likely to be teenagers, multiparous, without a married or de facto partner, public patients and smokers. Births in rural areas declined, particularly among women aged 20-34 years. Infants born to mothers in remote communities were at increased odds of stillbirth and low Apgar scores (all women) and small-for-gestational- age (SGA) (Indigenous women only).

CONCLUSIONS

The profile of pregnant women in rural NSW is different from their urban counterparts and is consistent with relative socioeconomic disadvantage and possibly suboptimal maternity services in some areas. While increased risk of SGA is associated with environmental factors such as smoking and nutrition, the reasons the increased risk of stillbirth are unclear. Although there does not appear to be an increase d risk of preterm birth for rural women this may be masked by transfer of high risk pregnancies interstate.

IMPLICATIONS

Maternity services need to be available and accessible to all rural women with targeting of interventions known to reduce low birthweight and perinatal death.

Socioeconomic status and health in Australia

Consistent with international evidence, the findings of Australian research show that socioeconomically disadvantaged groups experience significantly higher mortality and morbidity rates. Despite marked improvements in the health of all segments of the Australian population in recent decades, during this same period there has also been an increase in socioeconomically related mortality inequalities for some conditions. Socioeconomically disadvantaged groups are more likely to engage in health-damaging behaviours, experience poorer psychosocial health, make less use of the healthcare system for preventive purposes, and have a more adverse risk factor profile. These are the main contributing factors to the poorer physiological health of low socioeconomic groups. At present, our knowledge of how socioeconomic status and health are related is limited. A necessary step in improving our understanding of this issue is to draw together all the empirical evidence and use it as the basis for developing a theory of socioeconomic health inequalities. We present a conceptual framework to facilitate this process.

Socioeconomic status and infant mortality in Australia: a national study of small urban areas, 1985-89

This study uses small-area data for the period 1985-89 to examine the relationship between socioeconomic status and infant mortality in each of the mainland State capital cities of Australia. An unweighted OLS regression analysis based on 195 Statistical Local Areas (SLAs) that recorded five or more deaths over the reference period shows that standardised infant mortality ratios were significantly higher in areas with greater concentrations of low income families. This relationship was independent of the effects of low birthweight, Aboriginality, ethnicity and variability between each of the capital cities. To test for the robustness of this result a sensitivity analysis was undertaken. This involved (a) performing a Principal Components Analysis on a wide range of sociodemographic variables to derive factor scales that were subsequently included in a regression analysis, (b) using weighted least-squares regression and a Poisson generalised linear model and (c) including in the analysis all SLAs irrespective of the number of infant deaths. The sensitivity analysis supported the results of this study, thus validating the observed association between the socioeconomic characteristics of urban areas and their rate of infant mortality. Despite marked reductions in overall rates of infant mortality over the last century in Australia. socioeconomic disparities were still evident during the mid-to-late 1980s. Whether and to what extent this situation persisted during the early-to-mid 1990s will be known in the near future when the next collection of area-based data are publicly released. The results of this study, therefore, represent an important baseline against which more contemporary national trends can be monitored.