Placental abruption in immigrant women in Norway: A population-based study

Abstract

Introduction: Placental abruption is a serious complication in pregnancy. Its incidence varies across countries, but the information of how placental abruption varies in immigrant populations is limited. The aims of this study were to estimate the incidence of placental abruption in immigrant women compared with non-immigrants by maternal country and region of birth, reason for immigration, and length of residence.

Material and methods: We conducted a nationwide population-based study using data from the Medical Birth Registry of Norway and Statistics Norway (1990-2016). The study sample included 1 558 174 pregnancies, in which immigrant women accounted for 245 887 pregnancies and 1 312 287 pregnancies were to non-immigrants. Crude and adjusted odds ratios with 95% CI for placental abruption in immigrant women compared with non-immigrants were estimated by logistic regression with robust standard error estimations (accounting for within-mother clustering). Adjustment variables included year of birth, maternal age, parity, multiple pregnancies, chronic hypertension, and level of education.

Results: The incidence of placental abruption decreased during the study period for both immigrants (from 0.68% to 0.44%) and non-immigrants (from 0.80% to 0.34%). Immigrant women from sub-Saharan Africa had an adjusted odds ratio of 1.35 (95% CI 1.15-1.58) compared with non-immigrants for placental abruption, whereas immigrant women from Ethiopia had an adjusted odds ratio of 2.39 (95% CI 1.67-3.41). We found a small variation in placental abruption incidence by other countries or regions of birth, length of residence, and reason for immigration.

Conclusions: Immigrant women from sub-Saharan Africa, especially Ethiopia, have increased odds for placental abruption when giving birth in Norway. Reason for immigration and length of residence had little impact on the incidence of placental abruption.

Keywords: country of birth; epidemiology; immigration; obstetrics; perinatology; placental abruption.