The study, led by researchers at Newcastle University and the Regional Maternity Survey Office, suggests that as many as 1-in-13 deliveries to women with Type 1 or Type 2 diabetes involves a major congenital anomaly, also known as a birth defect.
The analysis showed that the risk of a birth defect in the pregnancies of women with Type 1 or Type 2 diabetes was 7%, compared to an average of around 2% in pregnancies in which the mother did not have diabetes. The chance of a birth defect was reduced significantly in women with diabetes who had blood-glucose levels within the recommended ranges -- which, according to Diabetes UK, has highlighted the importance of healthcare teams encouraging women who are thinking of becoming pregnant to get their blood-glucose level as low as is safely possible.
But the researchers and Diabetes UK have emphasized that, while concerning, this still means that the vast majority of pregnancies in women with diabetes do not involve a birth defect. The study also showed that blood-glucose levels around the time of conception were the most important factor predicting risk of congenital anomaly.
The findings have prompted Diabetes UK to urge women with diabetes who are considering becoming pregnant to make sure they understand the importance of careful planning.
"The risk of problems can be reduced by taking extra care to have optimum glucose control before becoming pregnant," stated Ruth Bell, the study's lead researcher. "Any reduction in high glucose levels is likely to improve the chances of a healthy baby." Previous research has established that having diabetes increases the chance of birth defects, but this is one of the first studies to quantify the effect of glucose levels on risk.
The study involved an investigation of the recorded outcomes of 401,149 pregnancies, including 1,677 pregnancies in women with diabetes, between 1996 and 2008 in the north of England.
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Diabetologia, Feb. 2012