Mother's social class and perinatal problems in a low-problem area.

This study reports the variation in perinatal problems related to social class in one area in Finland. Data on length of gestation, birthweight, one-minute Apgar score, and need for special care in relation to social class were obtained from a large clinical trial (n = 2912) on iron prophylaxis during pregnancy. Social class was determined from the woman's own occupation and education. Occupation was obtained from the women themselves and classified as upper white collar, lower white collar I, lower white collar II, and workers; entrepreneurs, students and women with no information were excluded. Education was obtained by record linkage to the national education register, and all women were classified by the years normally required to attain a certain level: greater than or equal to 13, 12, 10-11, and less than or equal to 9 years of education. Adjusted for age and parity, a week U-shaped curve was found for gestation length and birthweight, best results being found for the women in the second highest social class. The lower the social class, the more infants with poor Apgar scores. As potential intervening variables we studied marital status, pre-pregnancy weight, smoking, and haematocrit in the 28th week of pregnancy. Their inclusion in multivariate analyses influenced only slightly the differences in perinatal problems between the groups. Our results suggest that in Finland there are still differences in perinatal problems between social classes, but that the relationship is not always linear.