Classification differences and maternal mortality: a European study

Background To compare the ways maternal deaths are classified in national s tatistical offices in Europe and to evaluate the ways classification affect s published rates. Methods Data on pregnancy-associated deaths were collected in 13 European c ountries. Cases were classified by a European panel of experts into obstetr ic or non-obstetric causes. An ICD-9 code (International Classification of Diseases) was attributed to each case. These were compared to the codes giv en in each country. Correction indices were calculated, giving new estimate s of maternal mortality rates. Subjects There were sufficient data to complete reclassification of 359 or 82% of the 437 cases for which data were collected. Results Compared with the statistical offices, the European panel attribute d more deaths to obstetric causes. The overall number of deaths attributed to obstetric causes increased from 229 to 260. This change was substantial in three countries (P < 0.05) where statistical offices appeared to attribu te fewer deaths to obstetric causes. Ln the other countries, no differences were detected. According to official published data, the aggregated matern al mortality rate for participating countries was 7.7 per 100 000 live birt hs, but it increased to 8.7 after classification by the European panel (P < 0.001). Conclusion The classification of pregnancy-associated deaths differs betwee n European countries. These differences in coding contribute to variations in the reported numbers of maternal deaths and consequently affect maternal mortality rates. Differences in classification of death must be taken into account when comparing maternal mortality rates, as well as differences in obstetric care, underreporting of maternal deaths and other factors such a s the age distribution of mothers.