Time is on whose side? Time trends in the association between maternal social disadvantage and offspring fetal growth. A study of 1 409 339 births in Denmark, 1981-2004.
BACKGROUND
Fetal growth is highly socially patterned and is related to health across the life course, but how the social patterns of fetal growth change over time remains understudied. The time trends in maternal social disadvantage in relation to fetal growth were examined in the context of a universal welfare state under changing macroeconomic conditions over a 24-year period.


METHODS
All births in Denmark from 1981 to 2004 were included, and the association between maternal social disadvantage and birthweight was examined for gestational age z-scores over time using linear regression.


RESULTS
All measures of social disadvantage were associated with decreased fetal growth (p<0.001), but with considerable differences in the magnitude of the associations. The association was strongest for non-Western ethnicity (-0.28 z-score), low education (-0.19), teenage motherhood (-0.14), single motherhood (-0.13) and poverty (-0.12) and weakest for unemployment (-0.04). The deficit in fetal growth increased over time for all associations except for unemployment. Also, the measures of social adversity increasingly clustered within individuals over time.


CONCLUSIONS
Maternal social disadvantage is associated with decreased fetal growth in a welfare state. Social disadvantage is increasingly clustered so that fewer pregnancies are exposed, but those exposed suffer a greater disadvantage in fetal growth. The economic upturn in the last decade did not appear to weaken the association between maternal social disadvantage and decreased fetal growth.
Mortensen
L H
LH
National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, Copenhagen K, Denmark. laust.mortensen@gmail.com
Diderichsen
F
F
Davey Smith
G
G
Nybo Andersen
A M
AM
D000293:Adolescent; D000328:Adult; D001724:Birth Weight; D003718:Denmark / Q000453:epidemiology; D004522:Educational Status; D004812:Epidemiologic Methods; D005260:Female; D005317:Fetal Growth Retardation / Q000453:epidemiology* / Q000209:etiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008423:Maternal Age; D009035:Mothers / Q000706:statistics & numerical data; D011203:Poverty / Q000639:trends; D012959:Socioeconomic Factors; D014478:Unemployment / Q000639:trends; D055815:Young Adult