[Low birth weight, stillbirth and congenital malformations. Social differences]

The aim of the study was to describe differences in life style variables according to socioeconomic groupings and to analyse the association between birth weight, stillbirth and congenital malformations according to the socioeconomic groupings for the father as well as the mother. It was conducted as a follow-up of 11,888 pregnant women in Odense and Aalborg, Denmark who were consecutively enrolled in the study from April 1984 to April 1987 as part of a community trial. Consecutively information regarding socioeconomic group and life-style factors were collected by means of self-administered questionnaires in the 36th week of gestation. Data on pregnancy outcomes were collected from birth certificates and medical records according to standardized search routines. It was found that women in the lower socioeconomic groups were younger, smaller, had a higher prepregnancy weight, smoked more and had a higher intake of coffee during pregnancy than women in higher socioeconomic groups. Better off women, on the other hand, had a higher consumption of alcohol, fish, and vegetables. Low birth weight was found to be negatively correlated to socioeconomic grouping. The lowest birth weights were found among babies born to unskilled and unemployed women even after adjustment for smoking habits, prepregnancy height and weight and a number of other potential confounders. Stillbirth and the prevalence of congenital malformations was not associated with socioeconomic grouping, but the amount of information was very limited regarding these outcomes. The study shows that socioeconomic status is especially a risk factor for low birth weight. This association is not only due to differences in life style factors of relevance for the outcome of pregnancy.