Obstetric considerations for women with pre-existing diabetes

Women with pre-existing diabetes should be under the care of a specialist obstetrician (preferably in a high-risk pregnancy unit).

Fetal growth and wellbeing should be assessed throughout pregnancy, particularly in the third trimester. Growth and wellbeing scans should be performed every 4 weeks from 28 weeks’ gestation as a minimum. More frequent scanning and use of other measures of fetal wellbeing may be required. If there is concern about intrauterine growth restriction, aim for blood glucose concentrations at the upper end of the target range.

Mode of delivery should be determined on obstetric grounds; the aim is for vaginal delivery unless there are obstetric reasons for caesarean section.

Timing of delivery must be determined on an individual basis. Generally, the aim is to deliver around 38 weeks’ gestation. Early delivery (around 36 to 37 weeks’ gestation, sometimes even earlier) is more likely to be needed in women in whom glycaemic targets are not achieved, or those with elevated blood pressure, microvascular complications of diabetes, a longer duration of type 1 diabetes, falling insulin requirements, or a fetus with intrauterine growth restriction or macrosomia.

Because most women with pre-existing diabetes need to deliver early, they are more likely to require antenatal glucocorticoids to improve fetal lung maturity. Women receiving glucocorticoids should be admitted to hospital; they need intensive blood glucose concentration monitoring and a significant increase in insulin doses. Follow local protocols (if available) or seek expert advice for management.