They also warn that these problems will get worse as the number of young women diagnosed with type 1 and type 2 diabetes continues to rise.
Researchers analysed deaths shortly after birth (perinatal mortality) and congenital anomalies in babies born to women with type 1 or type 2 diabetes who delivered between 1 March 2002 and 28 February 2003 in England, Wales, and Northern Ireland.
Of 2,359 women with diabetes, 1,707 had type 1 diabetes and 652 had type 2 diabetes. Women with type 2 diabetes were more likely to come from an ethnic minority group and from a deprived area.
Perinatal mortality was similar in babies of women with type 1 (31.7 per 1000 births) and type 2 diabetes (32.3 per 1000 births), and was nearly four times higher than that in the general maternity population.
The rate of major congenital anomaly (mainly heart and nervous system defects) was 46 per 1000 births in women with diabetes (48 per 1000 births for type 1 diabetes and 43 per 1000 for type 2 diabetes), more than double than that in the general maternity population.
Because of this increased risk, the authors say that women with diabetes should take a higher than usual dose (5 mg) of folic acid from before conception up to week 12 of pregnancy. They also suggest that pregnant women with diabetes should be routinely screening for heart defects.
In the past, type 2 diabetes has been viewed as a less serious condition than type 1 diabetes and may have been subject to less vigilant care, add the authors. However, in view of these findings, and the increasing prevalence of type 2 diabetes in young adults, raised awareness of the increased risk of adverse pregnancy outcomes in this group of women is needed.
This study is substantially larger than any previous ones in this field, but more work is needed to find out how women with either type of diabetes can best be enabled to improve the outcomes of their pregnancy, they conclude.