Interpretation
Reinebrant and colleagues’ seminal work14 provided a
comprehensive overview of the causes of stillbirth around the globe. In
our review, we built upon this foundation by investigating ethnic
variation of causes of stillbirth in high-income countries. While
perinatal outcomes in some ethnic minority groups appear to have
improved over time, disparities in stillbirth rates based on ethnicity
continue to persist in the majority of reported
cases.7-9, 34, 36, 39, 40, 49-59 Ethnicities with the
largest sample sizes (Caucasian, African and Hispanic) overall showed
similar proportions in the causes of stillbirth. Compared to
non-Indigenous Australians, Indigenous Australian women showed higher
frequencies of stillbirth attributed to other complications of labour
and delivery. This category includes stillbirth that has been attributed
to malpresentation, forceps delivery, vacuum delivery, caesarean
delivery or induction of labour. This is in agreement with a
population-based study from the Northern Territory, Australia which
demonstrated higher rates of emergency caesarean and malpresentation in
Indigenous mothers compared to non-Indigenous,60 but
contrary to the study by Kildea and colleagues who found Indigenous
Australian to have lower rates of instrumental delivery and induction of
labour.61 In our review, Asian and South Asian
ethnicities showed a larger proportion of stillbirths attributed to
complications of placenta, cord and membranes, in line with previous
work showing higher rates of placental insufficiency62and placenta praevia63 in women of Asian heritage.
However, the utility of the interpretation of differences observed in
Indigenous Australian, Asian and South Asian women is limited due to
their small sample sizes.
Our findings imply that the higher incidence of stillbirths observed in
minority ethnic groups in previous studies are likely to be a
consequence of factors other than intrinsic differences such as
culturally inappropriate antenatal care64 and higher
incidence of modifiable risk factors such as obesity, maternal smoking,
hypertension, and diabetes.12 The effect of the
migration experience and the associated socioeconomic disadvantage
migrants may face is difficult to dissect from intrinsic differences
between various ethnic groups, if any, with regards to stillbirth
outcomes.24, 65-67 Gibson-Helm and
colleagues68 found that after adjusting for
confounding factors such as age, parity, BMI and relative socio-economic
disadvantage, the difference in stillbirth rates between migrants and
women from host countries disappeared. These results, together with
findings from our study, suggest that socio-cultural-economic factors
may be more important in explaining the disparities in stillbirth rates
between ethnic groups rather than intrinsic differences.