The combined influence of parental education and preterm birth on school performance.

BACKGROUND: Social background and birth characteristics are generally found to be independently associated with school achievements but the underlying mechanisms are not fully understood. This study aimed to explore how parental education and shorter gestational age jointly influence school performance in a cohort of Swedish children. METHODS: 10,835 children born between 1973 and 1981 were studied, the third generation of the register-based Uppsala Multigenerational Birth Cohort. Ordinal logistic regression models were fitted to estimate OR of achieving middle and high grades in Swedish language at age 16 years, relative to low grade, by parental education and own gestational age, adjusting for potential confounders. RESULTS: In children from families with lower parental education, the adjusted OR of receiving a higher grade was 0.54 (95% CI 0.41 to 0.71) for preterm (<37 completed weeks) compared with full-term births. This estimate did not change when adjusted for several potential confounders (0.59; CI 0.44 to 0.79). When different cut-points were selected to define preterm birth, the estimated OR for those with low parental education decreased linearly from 0.83 (CI 0.72 to 0.96) using less than 39 weeks as the cut-point, to 0.52 (CI 0.30 to 0.90) using less than 35 weeks. There was no evidence of significant effects of shorter gestational age for children with parents from other educational groups. CONCLUSIONS: The disadvantage of shorter gestational age on the chance of achieving higher grades in Swedish language was confined to children from families in which none of the parents had higher education. This suggests that the detrimental influence of shorter gestational age on school performance in language may be avoidable

The first injustice : Socio-economic inequalities in birth outcome

Adverse birth outcomes like preterm birth and infant mortality are unevenly distributed across socio-economic groups. Risks are usually lowest in groups with high socio-economic status and increase with decreasing status. The general aim of this thesis was to contribute to the understanding of the relation between socio-economic status and birth outcomes, focussing on maternal education and class, studying a range of birth outcomes. More specific aims were to investigate the relation between maternal education and infant health, to study the combined influence of maternal childhood and adult social class on inequalities in infant health and to explore the contribution of maternal working conditions to class inequalities in birth outcomes. The studies are population based, focussing on singletons births 1973-1990. During the period under study, educational differences in birth outcomes increased, especially between those with the lowest and highest education. The low birth weight paradox emerged, suggesting that the distribution of determinants for low birthweight infants differs for these groups. Further, an independent association was found between maternal childhood social class and low birthweight and neonatal mortality, but not for postneonatal mortality. Since this was found for the two outcomes closest to birth, this indicates that the association is mediated through the maternal body. Finally, there is a contribution of maternal working conditions to class inequalities in birth outcome. Lower job control, higher job hazards and higher physical demands were all to some degree related to increased risk of the following adverse birth outcomes: infant mortality, low birthweight, very low birthweight, foetal growth, preterm birth, very and extremely preterm birth. Working conditions demonstrated disparate associations with the birth outcomes, indicating a high complexity in these relationships

The influence of maternal childhood and adulthood social class on the health of the infant

The aim of this study is to investigate how maternal childhood and adulthood social class contribute to social inequalities in low birth weight, neonatal mortality and postneonatal mortality. In particular I consider the combined influence of childhood and adult class, and compare outcomes with regard to the time distance from birth. Analyses were performed on a large sample of Swedish births from 1973 to 1990, restricted to infants of women with both childhood and adult class, classified as manual or non-manual. Logistic regression is used to compare odds ratios for social classes. The results indicate that manual maternal childhood class is consistently associated with higher risks for low birth weight and neonatal mortality, even when adult class was adjusted for. The influence of adult class was greater than that of childhood class for all health outcomes. Compared to higher/middle non-manual workers, unskilled workers in the service sector and workers in the manufacturing sector displayed the highest odds ratios for all adverse health outcomes. When both childhood and adult class were taken into account, social differences were greater for low birth weight and neonatal mortality than for postneonatal mortality. Maternal childhood class had more influence on low birth weight and neonatal mortality than on postneonatal mortality. I conclude that maternal childhood and adulthood social class are both independently associated with inequalities in health-related birth outcomes, and that social differences are greater for health outcomes closer to birth.Maternal social class Infant health Low birth weight Infant mortality Sweden

The contribution of maternal working conditions to socio-economic inequalities in birth outcome

The aims of this study were to examine the association between maternal working conditions and birth outcomes, and to determine the extent to which these contributed to class inequalities in six birth outcomes. We used an existing job exposure matrix developed from survey data collected in 1977 and 1979 to apply occupational-level information on working conditions to the national Swedish Registry, including approximately 280,000 mothers and 360,000 births during the period 1980-1985. Data were analysed using multivariate logistic regressions. Low levels of job control, high levels of physical demands and job hazards were more common in manual compared to non-manual classes. The self-employed had intermediate levels of such exposures. Job exposures, particularly low levels of job control, were generally and significantly associated with higher risks for low birthweight, very low birthweight, small for gestational age, all preterm, very preterm and extremely preterm births, but not with mortality. Compared to middle non-manuals (the reference group), lower non-manual and manual classes had higher risks for all birth outcomes, and these risks were nearly all significant. The highest odds ratios were found for skilled and unskilled manual workers in the manufacturing sector, with ratios between 1.35 and 2.66 (all significant). Job control explained a considerable proportion of inequalities in all birth outcomes. Job hazards contributed particularly to very low birthweight and extremely preterm birth, and physical demands to low birthweight and all preterm births. In conclusion, class differences in maternal working conditions clearly contributed to class differences in low birthweight (explained fraction 14-38%), all preterm births (20-46%), very (14-46%) and extremely (12-100%) preterm births. For very low birthweight and small for gestational age, there was a similar contribution in the manufacturing sector only. For all birth outcomes, class differences could still be detected after working conditions were taken into consideration.Working conditions Birth outcome Socio-economic inequalities Sweden

Birth outcomes and early-life social characteristics predict unequal educational outcomes across the life course and across generations

We investigated the effects of adverse birth characteristics and social disadvantage upon educational outcomes over the lifecourse and across generations.  Our subjects were 12,674 Swedish infants born 1915-1929 and 9,706 of their grandchildren born 1973-1980.  Within both cohorts, better school achievement (schoolmarks in elementary school) was predicted by: heavier birthweight, lower birth order, older mother, married mother and higher family social class.  These effects persisted after mutual-adjustment, and birth characteristics and family composition did not play a major role in explaining social class effects.  There were no independent effects of pre-term or twin status, but weak evidence of a disadvantage to post-term infants.  The predictors of education continuation (secondary school attendance and entrance to tertiary education) were very similar, with family composition and social class effects persisting even after adjusting for school achievement.   In cross-generational analyses, better educational outcomes in the grandchildren were predicted by heavier birthweight, lower birth order and higher social class in the grandparents.  These associations became non-significant and/or were substantially attenuated after adjusting for grandchild socio-economic position in childhood, suggesting that this was the major mechanism for this effect.  We conclude that multiple early-life characteristics predict educational outcomes across the lifecourse and across generations.  This includes birth characteristics and family composition effects which typically receive far less attention than socio-economic influences.  Most effects were remarkably stable across the half-century separating our cohorts, suggesting their potential relevance for understanding educational inequalities in populations around the world