Background: We sought to examine whether age at immigration and length of residence were associated with preterm and small-for-gestational age (SGA) delivery among immigrant women in Denmark. Methods: We included all live singleton deliveries from Danish-born women (1 626 880) and women from the five largest immigrant groups (68 936) from 1978 to 2007. Data from the Danish Medical Birth Registry were linked to: parental country of origin, length of residence and age at immigration. Linear and logistic regression models were used to estimate absolute and relative differences with Danish-born women as the reference group. Results: All immigrant groups had an increased risk of SGA delivery with the highest risk among Lebanese-, Somali- and Pakistani-born women: risk differences (RDs) and 95% confidence intervals [CI] per 1000 deliveries of 50.2 [95% CI 43.7, 56.7], 70.1 [95% CI 62.2, 77.9] and 85.7 [95% CI 78.5, 92.9]. Turkish- and Pakistani-born women had increased RDs of 1.8 [95% CI 0.5, 3.1] and 2.2 [95% CI 0.1, 4.2] for very preterm and RDs of 3.5 [95% CI 0.9, 6.1] and 10.2 [95% CI 5.9, 14.5] for moderate preterm delivery. Lebanese-born women had a decreased risk of very preterm delivery, RD of -1.9 [95% CI -3.5, -0.3] and Somali-born women a lower risk of moderate preterm delivery, RD of -7.8 [-12.0, -3.6]. No differences were seen for the remaining groups. The association with length of residence for most immigrant groups was U-shaped, with highest risks among recent and long-term residents. Conclusion: Immigration was more strongly related to SGA than to preterm delivery. Observed differences in birth outcomes varied by age at immigration and length of residency in Denmark. © 2012 Blackwell Publishing Ltd.

Immigration Preterm delivery small-for-gestational age delivery

Pakistan immigrant regression analysis Registries Maternal Age logistic regression analysis risk register human immigration risk assessment Premature Birth Denmark Turkey (republic) Time Factors Yugoslavia Residence Characteristics Lebanon Humans Infant, Newborn Emigrants and Immigrants female Infant pregnancy high risk population Infant, Low Birth Weight Article Infant, Small for Gestational Age major clinical study adult small for date infant Somalia Age Factors prematurity outcome assessment parity Birth Weight gestational age