Checks carried out on pregnant women with diabetes to reduce their risk of complications may not be good enough, a study suggests.
Pregnant women with diabetes have a higher risk of complications
Women with insulin dependent diabetes have a higher risk of problems during pregnancy.
These range from pre-eclampsia to having babies with birth defects.
The risks are highest when these women have high levels of glucose in their blood.
As a result, they are regularly monitored by medical staff during pregnancy.
The aim is to ensure that the women's blood sugar levels remain within recommended limits.
'Not good enough'
However, a study by doctors in The Netherlands suggests these limits may not be tight enough.
Dr Inge Evers and colleagues at the University Medical Center Utrecht examined the records of 323 Dutch women who became pregnant April 1999 and April 2000.
They had a blood sugar test in the first, second and third trimesters of their pregnancy.
They found high rates of complications in all of the women, even those whose blood sugar levels were within the recommended limits.
According to the doctors, the women were at least three times more likely to have babies with birth defects or suffer from pre-eclampsia compared to other women.
Writing in the British Medical Journal, they said the findings suggest that the current guidelines for treating these women are not good enough.
"Our study shows that such levels of control are not 'safe' enough," they said.
The doctors said there was growing evidence to suggest that women with insulin dependent diabetes should monitor their blood sugar levels continuously while they are pregnant to ensure they are stable.
A spokesman for Diabetes UK said: "This study highlights the importance of careful planning and very good blood glucose control for women with diabetes who are thinking about a pregnancy.
"This is vital to reduce the risk of problems for the baby.
"The risk cannot be removed altogether but by working with their doctor and nurse, from before conception, women with diabetes can have a perfectly healthy baby."