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Real risks identified for babies of mothers with gestational diabetes

Large study reveals scale of risk for diabetic mothers’ newborns

Adrian O'Dowd

Thursday, 16 February 2017

Babies born to women who have gestational diabetes have a higher risk of poor outcomes including death compared to non-diabetic mothers, concludes a large-scale study* published today in Diabetologia, the journal of the European Association for the Study of Diabetes.

The proportion of women who are overweight or obese is increasing in almost all countries worldwide at the same time as an increased risk of developing both type 2 diabetes (whether pregnant or not) and gestational diabetes (GDM).

Previous studies have analysed the links between GDM and adverse outcomes in babies, but very large studies that draw on an entire national database are rare.

A team of French researchers – Dr Sophie Jacqueminet of the Pitié-Salpêtrière Hospital, Assistance Publique - Hôpitaux de Paris, Professor Delphine Mitanchez, Armand Trousseau Hospital, AP-HP, Paris, and Cécile Billionnet, French National Health Insurance, Paris, France, and colleagues – wanted to look at this issue on a larger scale.

For the new study, the researchers studied all 796,346 deliveries taking place after 22 weeks in France in 2012 by extracting data from the hospital discharge database and the national health insurance system.

Within the cohort of 796,346 deliveries, 57,629 (7.24%) mothers had GDM and data linking the mother to the child were available for 705,198 deliveries (88% of the total).

Analysis showed that the risks of adverse outcomes were two to four times higher for babies of mothers with type 2 diabetes before pregnancy than for those with GDM.

The authors then adjusted their data, limiting the analysis to deliveries after 28 weeks to ensure all women diagnosed with GDM were included because diagnosis of GDM in most cases takes place at or after 28 weeks.

Following this adjustment, the increased risk of various complications for mothers with GDM versus mothers without GDM were:

  • preterm birth 30%
  • caesarean section 40%
  • pre-eclampsia/eclampsia 70%
  • babies born significantly larger than average size 80%
  • respiratory distress 10%
  • birth trauma 30%
  • cardiac malformations 30%

They said that while these increased risks combined women with both insulin and diet-treated GDM, most of the increased risk was found in women with insulin-treated GDM.

When the researchers limited their analysis to normal-term deliveries (37 weeks), a moderately increased risk of death of the newborn baby was observed in women with GDM.

After excluding women suspected to have undiagnosed type 2 diabetes before pregnancy, the risk remained moderately increased only for those women with diet-treated GDM, with a 30% increased risk of the baby dying.

The researchers concluded: “We have clearly demonstrated that GDM is a disease related to adverse pregnancy outcomes and that most of the risks are higher in women with insulin-treated GDM.

“By restricting analysis to deliveries after 37 weeks and excluding cases of type 2 diabetes that were undiagnosed before pregnancy, we identified a moderate increase in risk of death to the newborn baby in women with GDM treated with diet only. Although more investigation is needed, this study helps illuminate the controversy about timing of delivery in GDM pregnancy.”

Dr Emily Burns, research communications manager at Diabetes UK, said: “Research like this can help us find potential ways to overcome the risks that women with gestational diabetes face.

“The overall risk of complications during pregnancy for these women is relatively low, but we need to eliminate it completely.”

* Billionnet C, Mitanchez D, Weill A, et al. Gestational diabetes and adverse perinatal outcomes from 716,152 births in France in 2012. Diabetologia, 2017. DOI 10.1007/s00125-017-4206-6

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