Preterm birth and low birthweight among children of Swedish and immigrant women between 1978 and 1990.

The aim of the study was to estimate the occurrence of low birthweight (LBW) and preterm birth among immigrant and Swedish women in Sweden. Eligible for analysis were all 1,270,407 singleton births in Sweden between 1978 and 1990 to mothers aged between 15 and 44 years, whose own country of birth was known. The mothers of the children were born in Sweden (88.2%), or had immigrated from Finland (4.4%), other Scandinavian countries (1.2%), Western Europe or North America (1.3%), Eastern Europe (1.8%), the Middle East and North Africa (1.7%), Central and South America (0.6%), Asia and the Pacific Islands (0.6%), or Sub-Saharan Africa (0.2%). Multiple logistic regression was used to model LBW and preterm birth categorical outcomes. Each immigrant group was compared with the Swedish group. Odds ratios (ORs) for LBW were 1.13 (95% CI 1.04, 1.22) for Asia and the Pacific Islands, 1.21 (1.05, 1.38) for Sub-Saharan Africa and 0.89 (0.86-0.93) for Finland. Odds ratios for preterm birth were 1.15 (1.08-1.23) for immigrants from Asia and the Pacific Islands and 1.08 (1.04, 1.13) for immigrants from Eastern Europe. Remarkably small differences were found between immigrant women and native Swedish women.