Gestational diabetes: Study finds testing should be earlier in pregnancy

pregnant woman in nursery

What was the aim of the study?

The prospective study, published in the journal Diabetes Care, investigated whether an unborn baby experiences overgrowth before a pregnant woman is diagnosed with gestational diabetes (GD). The study also looked at the relationship between GD and the mother’s weight. The unborn babies’ abdominal circumference (AC) and head circumference (HC) was measured via ultrasound at 20 and 28 weeks of gestational age.

What is gestational diabetes (GD)?

Diabetes is a condition characterised by high glucose levels in the bloodstream. When it begins or is first recognised during pregnancy, it is called GD. Women who develop GD are either unable to produce enough insulin or are unable to overcome a resistance to insulin. As a result, glucose builds up in their bloodstreams. High blood glucose levels can cause many health problems including pregnancy related hypertension (high blood pressure), pre-eclampsia, as well as larger babies which need to be delivered by induction or caesarean section. In addition, women with GD also have a higher risk of preterm deliveries. Women who have experienced GD are at increased risk of developing Type 2 diabetes later in their life. In addition, the babies born to women with GD also have an increased risk of developing Type 2 diabetes.

How many participants were included in the study?

The study was part of the Pregnancy Outcome Prediction Study, and included 4069 women, with 171 (4.2%) diagnosed with GD at or beyond 28 weeks.

What were the results?

The study found that while there was no indication in the size of the unborn baby at 20 weeks and a mother developing GD, unborn babies of women subsequently diagnosed with GD grew excessively between 20 and 28 weeks. In addition, unborn babies of women who were obese but were not diagnosed with GD were twice as likely to be big at 28 weeks. Women who were obese and also had GD had an almost 5-fold risk of their unborn babies having excessive growth by 28 weeks.

What do the researchers say?

The researchers concluded that “babies of women subsequently diagnosed with gestational diabetes are already abnormally large by the time their mothers are tested for the disease”. “Given the risk of complications for both mother and child from gestational diabetes, our findings suggest that screening women earlier on in pregnancy may help improve the short and long term outcomes for these women.”

What does it mean for women?

This particular study was based in the UK where women are typically screened for GD around the 28 week mark. In Australia, the majority of women undergo screening between 24-28 weeks. If women have one or more risk factors of GD, they may have a blood glucose test in early pregnancy, followed by a test at 24 weeks.

The study suggests that routine testing for GD should perhaps take place earlier in the pregnancy, as at present, by the time a diagnosis of GD is made the unborn baby will have already been affected. If women were diagnosed earlier in their pregnancy, the condition could be managed though a high-fibre and low-glycaemic (low GI) diet, and regular exercise.

Last updated: June 2016

© Women's Health Queensland Wide Inc. This article was written by Kirsten Braun and reviewed by the Women's Health Queensland Wide editorial committee in June 2016. It was first published in Health Journey Issue 2 2016.



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