Introduction
Placental abruption is a rare but serious complication affecting 3 to 10
per 1000 pregnancies worldwide (1, 2). It is a clinical diagnosis
defined as partial or complete detachment of the placenta before
delivery (2). The complication is associated with maternal and perinatal
morbidity and mortality and accounts for around 10% of all perinatal
deaths in developed countries (2).
The most common risk factors
include hypertension (3), pre-eclampsia (4), smoking (5) and the
extremes of maternal age (1, 2). A genetic predisposition also seems to
be implicated; women experiencing abruption in one pregnancy have an
11-fold increased risk of having an abruption in a subsequent pregnancy
(5, 6). Abruption also occurs however, in the absence of these factors.
Knowledge about additional contributing factors is important to better
explain the variation of this complication in the population.
In Europe, immigrant women represent a significant proportion of all
childbearing women (7) and in Norway, 29% of all births in 2019 were to
immigrant women (8). Immigrants comprise a heterogeneous group, with
diverse backgrounds and immigration reasons and they differ in relation
to the known risk factors for placental abruption, including
hypertension and smoking (9). Refugees are considered a vulnerable group
for adverse pregnancy outcomes (10), while women immigrating for work or
educational reasons may have equivalent or even better outcomes than the
receiving population (11). Some immigrants also appear to have better
health upon arrival than the host population though this may worsen over
time (9).
Few studies have compared the occurrence of placental abruption between
immigrant and non-immigrant women. Among those who have, an increased
risk has been found for black women compared to white women (2, 12), and
the risk of abruption for immigrants as a group seems to increase with
length of residence in the receiving country (13). However, the analyses
in these studies have not been performed according to specific maternal
country or region of birth nor by reason for immigration, so potential
variations in placental abruption may be masked in grouping all
immigrant women together. The aims of this study were to estimate the
incidence of placental abruption in immigrant women in Norway compared
to non-immigrants by maternal country and region of birth, reason for
immigration and length of residence.