New analysis of data from the Sands-funded POP study, carried out by researchers at the Department of Obstetrics & Gynaecology, University of Cambridge, suggests that testing for pregnancy diabetes (gestational diabetes) earlier in pregnancy could help cut the risk of stillbirth and health problems.

When a mother has gestational diabetes, there is a higher level of sugar (glucose) circulating in the mother and baby’s blood. As a result, the baby can grow larger than would be normal, putting the mother and the baby at risk of problems during pregnancy and labour. A baby who is larger than expected (called ‘large for gestational age’) also has an increased risk of stillbirth. And a child who has been exposed to high blood sugar levels during pregnancy is more likely to be obese.

The analysis looked at the size of babies on ultrasound scans at 20 and 28 weeks, and identified the babies whose mothers developed gestational diabetes during the pregnancy. The results showed that at 20 weeks there were no differences between babies in pregnancies with or without gestational diabetes. But by 28 weeks, babies whose mothers had gestational diabetes were more likely to be larger than normal, showing that gestational diabetes starts affecting babies before 28 weeks. This is an important finding because at the moment most women are tested for gestational diabetes at around 28 weeks of pregnancy. But the results from this analysis suggest women should be tested earlier, so that treatment can be started sooner if needed (gestational diabetes is usually managed with diet and exercise, though some women may need medication to control their blood sugar levels). A study to look at the effects of earlier testing is the next step.

Janet Scott, Research and Prevention Lead for the stillbirth charity Sands said: "We know that good risk assessment is crucial to avoiding harm to mothers and babies. We welcome these important findings, which show that it may be possible to reduce the risks from gestational diabetes with more timely identification and intervention.  We are delighted to have supported this research, funded with donations from bereaved families."

The work was carried out by researchers at the Department of Obstetrics & Gynaecology, University of Cambridge, and was supported by the National Institute for Health Research (NIHR), Cambridge Comprehensive Biomedical Research Centre and Sands.

Sovio U, Murphy HR, Smith GCS. Accelerated fetal growth prior to diagnosis of gestational diabetes mellitus: a prospective cohort study of nulliparous women. Diabetes Care 2016: doi: 10.2337/dc16-0160