Little attention has been paid to the ecological effects of unemployment, despite strong theory suggesting that being socially or economically connected to unemployed persons can induce illness. Theory suggests, for example, that the labor market experience of adult males should affect maternal and infant health. We advance this line of inquiry by testing the hypothesis that quarterly increases in unemployment among Norwegian and Swedish males were associated with increased incidence of very low weight births from 1973 through 1995. Results support the hypothesis. We estimate that approximately 188 very low weight births could have been averted in Norway, and about 329 in Sweden, if quarterly increases in male unemployment had been constrained to the median over the 23-year period. Our findings imply that the social cost of unemployment may be underestimated by focusing on unemployment as an individual risk factor.