Are there differences in birth weight between neighbourhoods in a Nordic welfare state?

Background: The objective of this cohort study was to examine the effect on birth weight of living in a disadvantaged neighbourhood in a Nordic welfare state. Birth weight is a health indicator known to be sensitive to political and welfare state conditions. No former studies on urban neighbourhood differences regarding mean birth weight have been carried out in a Nordic country.
Methods: A register based on individual data on children's birth weight and maternal risk factors was used. A neighbourhood characteristic, i.e. an aggregated measure on income was also included. Connections between individual- and neighbourhood-level determinants and the outcome were analysed using multi-level regression technique. The study covered six hundred and ninety-six neighbourhoods in the three major cities of Sweden, Stockholm, Göteborg and Malmö, during 1992-2001. The majority of neighbourhoods had a population of 4 000-10 000 inhabitants. An average of 500 births per neighbourhood were analysed in this study.
Results: Differences in mean birth weight in Swedish urban neighbourhoods were minor. However, gestational length, parity and maternal smoking acted as modifiers of the neighbourhood effects. Most of the observed variation in mean birth weight was explained by individual risk factors.
Conclusion: Welfare institutions and benefits in Sweden might buffer against negative infant outcomes due to adverse structural organisation of urban neighbourhoods.