Caesarean section by immigrants' length of residence in Norway: a population-based study

Background: Immigrants to Europe account for a significant proportion of births in a context of rising caesarean rates. We examined the risk of planned and emergency caesarean section (CS) by immigrants' length of residence in Norway, and compared the results with those of non-immigrants. Methods: We linked population-based birth registry data to immigration data for first deliveries among 23 147 immigrants from 10 countries and 385 306 non-immigrants between 1990-2009. Countries were grouped as having low CS levels (<16%; Iraq, Pakistan, Poland, Turkey, Yugoslavia, Vietnam) or high CS levels (>22%; the Philippines, Somalia, Sri Lanka, Thailand). Associations between length of residence and planned/emergency CS were estimated as relative risks (RR) with 95% confidence intervals (CI) in multivariable models. Results: In the immigrant group with low CS levels, planned, but not emergency, CS was independently associated with longer length of residence. Compared with recent immigrants (<1 year), the risk of planned CS was 70% greater among immigrants with residency of 2-5 years (RR 1.70, CI: 1.19-2.42), and twice as high in those with residency of >= 6 years. (RR 2.01, CI: 1.28-3.17). Compared with non-immigrants, immigrants in the low group with residency <2 years had lower risk of planned CS, while those with residency >2 years had greater risk of emergency CS. In the high group, the risk of planned CS was similar to non-immigrants, while emergency CS was 51-75% higher irrespective of length of residency. Conclusion: Efforts to improve immigrants' labour outcomes should target subgroups with sustained high emergency caesarean risk.