578 Increased risk of adverse maternal pregnancy outcomes among undocumented migrants in Norway

Abstract OP 29: Health Status 4, B302 (FCSH), September 4, 2025, 16:00 - 17:00 Aim Migrants are known to have an increased risk of adverse complications during delivery. However, it is not known whether undocumented migrants have a different risk profile compared to documented migrants and non-migrants. This study aimed to gain better knowledge about undocumented migrants’ reproductive outcomes, which is crucial to enable targeted preventive interventions. Method We performed a historical register-based population study based on numbers from the Medical Birth Registry of Norway (MBRN) from 1999 to 2020. Women aged 18–49 years with singleton births were included, in total 1,247,537 births. Legal status, i.e., undocumented migrants (without a Norwegian identity number), documented migrants (with a Norwegian identity number and born abroad) and non-migrants (with a Norwegian identity number and born in Norway), was used as the exposure. We used logistic regression to estimate the association between legal status and adverse maternal birth outcomes. Results In total, 5856 undocumented migrant women gave birth during the study period, representing 0.5 % of all births in Norway. Undocumented migrants had an odds ratio (OR) of 1.39 (95 % Confidence Interval (CI) 1.28–1.51) for an acute CS and OR = 0.86 (95 % CI 0.76–0.98) for a planned CS, both compared to non-migrants. Similarly, the OR for severe postpartum haemorrhage (PPH) was 1.22 (95 % CI 1.03–1.43) and OR 0.70 (95 % CI 0.57–0.87) for anal sphincter injury. None of the results were significantly different when documented migrants were used as the reference group. Conclusion Undocumented migrants have an increased risk of adverse maternal birth complications compared to non-migrants, but not different from documented migrants. This indicates that for maternal birth complications, factors concerning migration may affect the risk profile to a larger degree than legal status.