Commentary on ‘Increased risk of severe maternal morbidity (near-miss) among immigrant women in Sweden: a population register-based study’
In this nationwide study from Sweden, an increased risk of severe maternal morbidity in women who had migrated from low-income countries compared with native Swedish women is confirmed with an odds ratio of 2.3 (95% confidence interval 1.9–2.8). Although only based on registers, its nationwide aspect is important, because most studies addressing ‘maternal near-miss’ are facility-based and originate from tertiary-care centres (Tunçalp et al. BJOG 2012;119:653–61).
This study will be used to compare maternal morbidity in Sweden with that of other settings. This comparison is difficult, because case selection is at stake. One could ask why women with multiple pregnancies or very preterm births (<28 weeks of gestation) are excluded. In addition, women from an unknown country of origin are less likely native Swedish women, but are excluded from analysis.
Classification of severe maternal morbidity is complicated, as can also be judged from this paper: ‘The clinical diagnosis … were acute renal failure, …, respiratory failure, shock, cerebrovascular failure, …, severe (pre-)eclampsia, uterine rupture, …’. Both eclampsia and uterine rupture may manifest themselves with renal, respiratory and cerebrovascular failure. From audit of organ dysfunction only, no lessons can be learnt as to what we should do to prevent the events leading to the dysfunction. Audit of clinical criteria such as ‘eclampsia’, however, will allow us to answer relevant questions such as: was magnesium sulphate given in time to a woman suffering from severe pre-eclampsia in order to prevent eclampsia?
With the aim to develop standard definitions and uniform identification criteria, the World Health Organization developed a Maternal Near-Miss Approach, concentrating on women presenting with features of organ dysfunction. One of their goals is to enable comparisons across different settings, particularly including low-income countries. The near-miss classification system has been applied now in a number of countries including Brazil and South Africa. A recent study from Malawi, however, indicates that this approach may not be sufficient to detect severe maternal morbidities in low-income countries (Van den Akker et al. PLoS One 2013;8:e54805). In those places where near-misses occur most frequently, organ dysfunction is not easily detected. Moreover, efforts should be directed towards the prevention of organ dysfunction.
The World Health Organization Maternal Near-Miss Approach can be difficult to apply in low-income settings or poorly resourced health systems. For example, it includes the use of more than four units of blood for transfusion as a criterion for organ dysfunction, while at the same time the use of any blood product would suffice to include a woman as a case of severe maternal morbidity. More than four units of blood is often used as a criterion in studies from high-resource countries. This leads to the contradictory conclusion that haemorrhage has a low prevalence in resource-poor settings and seriously underestimates its devastating effects (Nelissen et al. PLoS One 2013;8:e61248).
The Swedish paper adds to the ongoing discussion about an appropriate approach to the study of severe maternal morbidity. The last word on this topic, however, has not yet been said.