Spontaneous abortions by occupation and social class in Finland

Int J Epidemiol. 1980 Jun;9(2):149-53. doi: 10.1093/ije/9.2.149.

Abstract

A hospital discharge registry covering all general hospitals in Finland was used in the study of spontaneous abortions. Spontaneous abortions were analysed by the women's occupation and socio-economic class for 1973-75 inclusive. The risk of spontaneous abortion increased from social class 1 to 4 by about 50%. The occupational groups with an increased frequency of spontaneous abortions included industrial and construction work, agriculture, forestry and fishing, sales, transport and communication, services, and students and trainees. Decreased frequency of spontaneous abortions was noted among housewives, and in managerial and clerical occupations. The results suggest that socio-economic factors contribute to the rate of spontaneous abortions analogous to their known adverse effects on pre-term birth, birth weight and perinatal mortality.

PIP: The application of a hospital discharge registry covering all general hospitals in Finland to study spontaneous abortions is described. The frequency of spontaneous abortion in occupational and socioeconomic groups was analyzed from the registry. The data consisted of all inpatients admitted to Finnish hospitals for spontaneous abortion in 1973-1975. The Finnish National Board of Health maintains a computerized registry on all patients discharged from general hospitals. Data on patients treated for spontaneous abortions, induced abortions, and on women giving birth were extracted. The rate of spontaneous abortions increased with the age of the woman. In the active reproductive ages of 20-34 years the rate of spontaneous abortions (related to pregnancies) was around 7%. The ratio of spontaneous abortions to births was higher than the rate over all, particularly in older age groups, indicating the relative frequency of induced abortions at higher ages. Spontaneous abortions increased from social class 1 (age-standardized rate 5.88% and ratio 8.17%) to social class 4 (8.47 and 14.93%, respectively). Farmers, social class 5, had an age-standardized rate and ratio of 7.56 and 9.90%, respectively. Students and persons with unknown occupations, social class 6, had a total rate and ratio of 8.28 and 14.66%, respectively. The apparently high ratio in the 15-19 age group of social class 1 is based on small numbers and may be due to chance. The rate of spontaneous abortion was significantly increased among women employed in agriculture, forestry and fishing; among students and trainees; and industrial and construction workers. The rate significantly decreased in managerial and clerical occupations and among housewives, including farmers' wives. The ratios of spontaneous abortion showed larger differences between the occupations than the respective rates. In sum, study results revealed an increase in the frequency of hospitalized spontaneous abortions in lower social classes and in occupational groups involving demanding manual and physical work. The data indicate that environmental factors play a part in the etiology of spontaneous abortion.

MeSH terms

  • Abortion, Spontaneous / epidemiology*
  • Adult
  • Age Factors
  • Female
  • Finland
  • Humans
  • Occupations
  • Pregnancy
  • Social Class