Saving Mothers' Lives: - Public Health Agency for Northern Ireland

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20 Severe maternal morbidity - the Scottish experience 2003 to 2005
Discussion
The Scottish Confi dential Audit of Severe Maternal Morbidity has collected data prospectively using 14 welldefi
ned, consistent categories of morbidity for the triennium (2003-2005), contemporaneous with this maternal
death enquiry. The audit is funded by NHS Quality Improvement Scotland. Continuous data collection under
the auspices of a national agency, has two principal advantages. Firstly, aggregation of data over several
years means that meaningful national rates of rare outcomes such as eclampsia can be calculated. Secondly,
consistent methods mean that trends over time in overall rates of severe morbidity can be examined.
The causes of severe maternal morbidity found in our study differ from the causes of maternal death found
in the Confi dential Enquiries. Major haemorrhage accounted for 69% of our cases of severe morbidity
but for only 11% of Direct maternal deaths in the UK in the 2003 to 2005 triennium. In contrast, venous
thromboembolism was the principal cause of maternal death (28% of cases), but accounted for under
2% of our cases of severe morbidity. Thus, the pattern of morbidity and mortality appears to differ from
the continuum described by Pattinson 5 , with some clinical insults (e.g. major haemorrhage) being more
amenable to alteration by prompt and appropriate treatment than others.
The approach used by the Scottish Confi dential Audit relies on accurate and complete case identifi cation
at local hospital level. There have always been concerns that incident reporting systems under-estimate
the true level of reportable events. In order to improve reproducibility, we have a designated member of
staff within each unit with responsibility for reporting and we regularly update these participants. We would
anticipate that with increasing familiarity with the study, case ascertainment would improve. Improved
ascertainment may explain the apparent rise in the rate of severe morbidity.
Another explanation is that a rise in major obstetric haemorrhage has resulted from changes in the obstetric
population: increasing numbers of mothers with complex medical conditions, increasing age at childbirth,
increasing number of multiple pregnancies following assisted reproduction, and increasing number of
caesarean sections with subsequent placenta praevia and accreta. Data from Information Services of NHS
Scotland 10 show that the national rate of emergency caesarean section remained constant at 15.4% over
the three years of this study but the rate of elective Caesarean section rose year on year, from 8.8% in 2003
to 9.5% in 2005 (Chi-squared test for trend, p