Strengths and limitations
To the best of our knowledge, this is the first systematic review that
synthesised data on the ethnic variation of the causes of stillbirth in
high income nations and to standardise reporting of outcomes using the
ICD-10-PM classification. To increase the accuracy of identified causes,
we included only those studies that reported foetal autopsy and/or
placental pathology data to determine the actual cause of
stillbirth38 rather than associated risk factors, and
excluded studies that used surrogate markers of ethnic identity such as
mother tongue or language spoken at home. Mapping disparate causation
data from individual studies to the ICD-10-PM and subsequently pooling
results by meta-analysis allowed improved interpretation of findings and
easier comparison between ethnic groups.
Results from this study should be interpreted in the context of some
limitations. First, exclusion of studies reporting only associations
between various risk factors and stillbirth may have resulted in loss of
information and limited our ability to assess the full value of the
ICD-PM. Second, use of crude categories to define ethnicity may be
limited by being only proximal guides to experiences, practices, and
beliefs of individuals and may not capture the associated complex and
interrelated socioeconomic determinants such as education and employment
that may be driving disparities in stillbirth rates.27,
39-44 Inequalities in stillbirth between various ethnic groups have
been shown to reduce after acculturation and adoption of host
nationality,45 highlighting the limitation in
interpreting stillbirth data segregated by ethnicity. Third, differences
in causes of stillbirth between studies may be a consequence of
differences in classification rather than any important differences in
pathological processes per se. This is especially pertinent in the
context of the myriad classification tools available and used in various
studies, making regional and global comparisons difficult. The ICD-PM
itself faces challenges including insufficient differentiation of causes
from associated conditions and insufficient detail on maternal
conditions. Fourth, most data used in our analyses were collected more
than 10 years ago and may not reflect recent migration patterns and
demographic changes, and current socioeconomic and health care
environments. Finally, despite including studies investigating thecauses of stillbirths, we found considerable variation in autopsy
rate between studies with some studies reporting rates as low as 38%.
Previous studies have shown that ethnic minority groups have lower rates
of being asked for consent for a post-mortem study, and also lower rates
of consent when asked.46, 47 This may be due to
assumptions and/or actual differences in religious or cultural
observances and may reflect an inherent limitation in studies involving
minority ethnic groups and causes of stillbirth. Due to this limitation
it is also worth considering alternatives to post-mortem examination
which may be accessible in high income counties, such as
MRI,48 to assist in assigning cause of death when
post-mortem examination is declined.