Change in social status and risk of low birth weight in Denmark: population based cohort study
BMJ 1997; 315 doi: https://doi.org/10.1136/bmj.315.7121.1498 (Published 06 December 1997) Cite this as: BMJ 1997;315:1498
- Olga Basso, research fellow (ob{at}soci.aau.dk)a,
- Jørn Olsen, professora,
- Anne Mette T Johansen, statisticianb,
- Kaare Christensen, associate professorc
- a Danish Epidemiology Science Centre, Department of Epidemiology and Social Medicine, Aarhus University, Høegh Guldbergsgade 10, DK 8000 Aarhus C, Denmark
- b Danish National Board of Health, Copenhagen, Denmark
- c Centre for Health and Social Policy, Odense University, Denmark
- Correspondence to: Dr Basso
- Accepted 21 July 1997
Abstract
Objective: To estimate the risk of having a low birth- weight infant associated with changes in social, environmental, and genetic factors.
Design: Population based, historical cohort study using the Danish medical birth registry and Statistic Denmark's fertility database.
Subjects: All women who had a low birthweight infant (<2500 g) (index birth) and a subsequent liveborn infant (outcome birth) in Denmark between 1980 and 1992 (exposed cohort, n=11 069) and a random sample of the population who gave birth to an infant weighing ≥2500 g and to a subsequent liveborn infant (unexposed cohort, n=10 211).
Main outcome measures: Risk of having a low birthweight infant in the outcome birth as a function of changes in male partner, area of residence, type of job, and social status between the two births.
Results: Women in the exposed cohort showed a high risk (18.5%) of having a subsequent low birthweight infant while women in the unexposed cohort had a risk of 2.8%. After adjustment for initial social status, a decline in social status increased the absolute risk of having a low birthweight infant by about 5% in both cohorts, though this was significant only in the unexposed cohort. Change of male partner did not modify the risk of low birth weight in either cohort.
Conclusion: Having had a low birthweight infant and a decline in social status are strong risk factors for having a low birthweight infant subsequently.
Key messages
The risk of having a subsequent low birthweight infant after the birth of a first is high, but changes in social factors may alter the risk
A decline in social status increases the risk of having a low birthweight infant, especially among women who have not previously had a low birthweight infant
A rise in social status is associated with a reduced risk of having a low birthweight infant
Women who have had a decline in social status need special attention in antenatal units
Footnotes
- Accepted 21 July 1997