Trends in socioeconomic differences in Finnish perinatal health 1991-2006.

BACKGROUND: Socioeconomic differences in perinatal health decreased in Finland in the late 1990s. Whether the decreasing socioeconomic differences in perinatal health observed in Finland in the late 1990s have continued in 2000-6 was studied. METHODS: The data were based on 965 443 births and 931 285 singletons recorded between 1991 and 2006 in the Finnish Medical Birth Register. Information on socioeconomic position was based on maternal occupation. Perinatal health was measured with six different indicators. RESULTS: The proportions of preterm, low birthweight and SGA (small-for-gestational-age) births remained stable during the study period, but decreased for LGA (large-for-gestational-age) births and perinatal death. After adjustment for maternal background variables, the socioeconomic differences in preterm and low-birthweight births decreased in the late 1990s and remained low thereafter. In 2003-6, blue-collar workers had a 14% (95% CI 7% to 22%) higher risk for preterm birth and a 25% (95% CI 16% to 34%) higher risk for low birthweight than upper white-collar workers. For SGA, the socioeconomic differences remained unchanged, and the excess risk for blue-collar workers was 44% (95% CI 31% to 58%) in 2003-6. For LGA, the socioeconomic differences increased, and the highest excess risks were obtained among lower white-collar (23%, 95% CI 15% to 33%) and blue-collar workers (24%, 95% CI 14% to 36%). The differences in perinatal mortality decreased until the late 1990s, but increased thereafter. In 2003-6, lower white-collar and blue-collar workers had the highest excess risks: 46% (95% CI 20% to 77%) and 44% (95% CI 13% to 83%), respectively. CONCLUSIONS: The trends in social inequality in perinatal health outcomes were diverging by indicator. The positive trend on diminishing socioeconomic differences found in the 1990s seems to have come to an end.

Social inequality in fetal growth: a comparative study of Denmark, Finland, Norway and Sweden in the period 1981-2000.

OBJECTIVE: To examine the socioeconomic patterns and time trends in fetal growth in Denmark, Finland, Norway, and Sweden from 1981 to 2000. DESIGN AND SETTINGS: Data on all live-born singleton births was drawn from national population registries in each of the four countries (Denmark n = 1,077,584; Finland n = 400,442; Norway n = 929,458; Sweden n = 1,761,562). MAIN OUTCOME MEASURE: Slope index of inequality (SII) and mean differences in birthweight for gestational age, SII and risk differences in small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants. RESULTS: In all countries, gradients in fetal growth by parental education existed. Low parental education was associated with lower birthweight, increased risk of SGA and decreased risk of LGA. Mother's education exerted the strongest influence on outcomes, whereas father's education had a weaker effect. The educational gradients as measured by the SII were generally steepest in Denmark, followed by Norway, Sweden, and Finland. From 1981 to 2000, the educational gradients in birthweight decreased in all countries, except Denmark where it increased. All countries experienced small decreases in the educational gradient in SGA over time. CONCLUSION: The economic recession in Denmark in the 1980s was concurrent with an increase in disparities in fetal growth, whereas the economic recession in Finland and Sweden in the early 1990s did not substantially increase the socioeconomic inequality in fetal growth. The economic growth in the later part of the 1990s may have diminished the socioeconomic inequality in fetal growth in Finland, Norway, and Sweden.

Decompression profile and bubble formation after dives with surface decompression: experimental support for a dual phase model of decompression.

The present study was initiated in order to determine the effect of decompression profiles on bubble formation following surface decompression using oxygen. Following an air dive to 496 kPa (130 fsw) for 90 minutes, three different profiles were tested in the pig; a USN staged decompression profile, a profile using linear continuous decompression with the same total decompression time as the USN profile (ABI) and a linear profile with half the total decompression time compared to the the first two (ABII). The subsequent surface decompression at 220 kPa lasted 68 minutes for all three schedules. The study demonstrated that, following final decompression, the two linear profiles produced the lowest amount of vascular gas, with the fastest profile producing significantly less bubbles in the Pulmonary artery than the other two. Similar results were obtained in the jugular vein. The results are in qualitative agreement with model simulation using the Reduced Gradient Bubble Model (RGBM), demonstrating that the controlling tissues are reduced from those with a half time of 40 minutes using the USN procedure to 5 minutes using the fastest linear profile.

The association between maternal education and postneonatal mortality. Trends in Norway, 1968-1991.

BACKGROUND: This study examines whether the association between maternal educational level and postneonatal death has changed over time. METHODS: All single survivors of the neonatal period in Norway in three periods, 1968-1971, 1978-1981 and 1989-1991 were studied. There were 582 046 births and 1717 postneonatal deaths. Logistic regression analyses were applied. RESULTS: There has been an increasing inverse relationship between maternal educational level and postneonatal mortality in recent years. There was no statistically significant association between educational level and postneonatal mortality in the late 1960s. In the second period (1978-1981) the association is statistically significant for first-born children. In the third period (1989-1991) postneonatal mortality for first-born and later-born children was associated with maternal educational level, with adjusted odds ratios of 2.5 and 2.1 respectively. The overall level of education has increased tremendously, and the proportion of women with the lowest level of education has decreased from 56.3 to 10.7% in the period under study. CONCLUSIONS: The underlying causes of changes in the impact of educational level are hard to determine and are indicative of the complexity of using maternal educational level as an indicator of social status over time. Possible mechanisms by which certain variables may covary with educational level, and thus have an adverse effect on postneonatal mortality, are discussed. The fact that the inverse association between educational level and postneonatal mortality has increased over time should be a matter for concern. It may indicate that the growth of the welfare state has not reached all segments of the population.

Marital status as a risk factor for fetal and infant mortality.

In order to study pregnancy outcome for married versus unmarried mothers when controlling statistically for maternal age, educational level, socioeconomic status and income, a total of 93,800 firstborn singleton births in 1978-1982 were examined. The unmarried mothers were younger, less well educated and had a lower socioeconomic status than the married mothers. The stillbirth, neonatal, and postneonatal mortality rates were higher among offspring of unmarried mothers. After taking sociodemographic factors into account, marital status was found to be associated with postneonatal mortality. The adjusted odds ratio for postneonatal mortality was 1.5. Our results indicate the importance of marital status as a demographic risk factor even in a welfare society. There is a need to identify specific risk behaviours associated with the life styles of unmarried mothers. Hopefully our findings will provide information that can be used for future programmes of prevention, especially for the mother and her child during the first year of life.

Is the higher postneonatal mortality in lower social status groups due to SIDS?

In order to study the influence of sociodemographic factors, postneonatal mortality of all live births surviving the neonatal period registered in the Norwegian Medical Birth Registry in 1978-1982 were examined (n = 209,030). Postneonatal deaths (n = 634) were divided into two categories; deaths due to the sudden infant death syndrome (SIDS) (n = 359) and deaths due to other causes (non-SIDS) (n = 275). SIDS and non-SIDS deaths showed different relationships to sociodemographic factors, and the associations appeared to be different for first-born and later born children. SIDS mortality was highest for first-born offspring when the mother was young (adjusted relative risks (RR) 2.3) and had a low educational level (adjusted RR 4.9). For later-born offspring no association between maternal educational level and SIDS was found, while young maternal age (adjusted RR 4.4) and unmarried status (adjusted RR 2.3) were closely associated with SIDS. In the multivariate model, however, there were no statistically significant associations between non-SIDS and sociodemographic factors for first-born or later-born children. Thus it appears that the increased postneonatal mortality in lower social groups can be explained by an association with SIDS.

Different effects of maternal and paternal education on early mortality in Norway.

In order to separate the effects of maternal and paternal education on pregnancy outcome, a total population of 97,526 single, firstborn infants and their parents was studied. Census information from 1980 was linked to the Medical Birth Registry for 1978-82. Children of parents with high education (> 12 years) were the most likely to survive the first year of life. There was a linear association between parental education and infant mortality. Examining parental education jointly, it was found that the father's educational level had the greatest impact on stillbirth. Mother's educational level seemed to be more closely associated with postneonatal mortality. Possible mechanism to explain the association between educational level and infant mortality are discussed.

No correlation in post-neonatal deaths for twins. A study of the early mortality of twins based on the Norwegian Medical Birth Registry.

The records of 10,204 pairs of twins born in Norway 1967-84 in the Norwegian Birth Registry were examined. The probabilities of stillbirth, neonatal death and post-neonatal death, conditional on the fate of the cotwin, were calculated. The neonatal death rate was four times increased when the cotwin was stillborn. When the cotwin died neonatally, the probability of postneonatal death was increased ninefold. The concordance rate for stillbirth and for neonatal death was above 0.4. In striking contrast, there was no correlation in postneonatal death for members of a twin pair. This finding suggests that genetic or common environmental factors play a minor role in the aetiology of post-neonatal death.