RT Journal Article SR Electronic T1 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 JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP 281 OP 285 DO 10.1136/jech.2008.076364 VO 63 IS 4 A1 L H Mortensen A1 F Diderichsen A1 G Davey Smith A1 A M Nybo Andersen YR 2009 UL http://jech.bmj.com/content/63/4/281.abstract AB 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.Conclusion: 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.