Background Perinatal mortality remains high among babies of mothers with type 1 and type 2 diabetes. The causes of death have not previously been described.

Aims

• To describe the causes of stillbirth and neonatal death in babies of women diabetes mellitus.

• To test the hypothesis that the causes of perinatal mortality are the same for women with type 1 and type 2 diabetes.

• To compare the currently applied classification systems with newer ‘alternative’ systems, with particular emphasis on numbers of ‘unexplained’ deaths.

Aims

Methods The case notes of women with pre-existing diabetes who had a stillbirth or neonatal death were identified during the Confidential Enquiry into Maternal and Child Health (CEMACH) report. Cause of death was extracted and classified by two reviewers independently.

Results Ninety three cases were analysed: 73 stillbirths, 20 neonatal deaths. The commonest cause of death was antepartum asphyxia (64 cases) followed by congenital anomaly (18 cases). Mortality due to congenital anomaly was less common in women with type 1 diabetes (15% of deaths vs 26%; rate ratio 0.37, 95% CI 0.15 to 0.95).

‘Alternative’ classification systems reduce ‘unexplained’ deaths, but the differences are predominantly in nomenclature.

Discussion This is the first description of the causes of perinatal mortality in women with diabetes at a national population level. Most deaths are still classified as ‘unexplained’. Further work is needed (i) to improve the classification for all babies, (ii) to understand better the mechanisms for these losses, in order that (iii) outcomes can be improved.