Fetal growth in GDM already ‘abnormal’ at 28 weeks

Wednesday, 20 Apr 2016

Screening pregnant women for gestational diabetes at 28 weeks could mean opportunities to prevent complications are being missed, particularly in women who are also obese, British research suggests.

According to the prospective cohort study of over 4,000 nulliparous women, those who screened positive for GDM at or after 28 weeks gestation were more than twice as likely to be carrying a fetus that had an abdominal circumference in the 90th percentile (adjusted relative risk 2.05 [95% CI 1.37–3.07]).

The risk was even higher when obesity was added in as a risk factor, with obese women with a GDM diagnosis having an almost five-fold increased risk (adjusted RR 4.52 [95% CI 2.98–6.85]).

“These data suggest that the onset of fetal growth disorder in GDM predates the usual time of screening” the study authors wrote in Diabetes Care.

It was plausible that earlier screening and intervention may result in lower risks of adverse outcomes, they said.

Diabetes in pregnancy expert Professor Robert Moses said that it was generally accepted that most of the abnormal fetal growth that happens with GDM occurs in the second trimester.

“So by screening at 28 weeks we are missing this, and this study has shown in an elegant way that this is the case” he told the limbic.

However Professor Moses, who is a Director of Diabetes Services at the Illawarra and Shoalhaven Local Health District in Wollongong, pointed out that the diagnostic criteria used in the study were different to current Australian guidelines.

“They were picking up the more severe cases. Our cut-offs are lower, so we are picking up more patients in the continuum of risk”, he said.

Furthermore Australian guidelines also recommended earlier screening for women at higher risk, which is around 50-60% of our obstetric population, said Professor Moses, who was involved in the development of the Australian Diabetes in Pregnancy Society (ADIPS) Consensus Guidelines for the Testing and Diagnosis of Gestational Diabetes Mellitus in Australia.

“I don’t think we need to change our practice based on these findings”, he said, “but this is another reason why women at higher risk need to be screened earlier”.

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