Becky McCall

September 15, 2016

MUNICH — Risk of perinatal death was increased by 30%, compared with the risk in nondiabetic mothers, in mothers with gestational diabetes who gave birth after 37 weeks, a large new cohort study from France shows.

This higher risk of the baby dying was the same regardless of whether the woman was treated with insulin for the gestational diabetes or not.

However, it was still lower than the risk of perinatal death in mothers with either type 1 diabetes or type 2 diabetes, reported Sophie Jacqueminet, MD, senior investigator from Hôpital Pitié-Salpétrière, Paris, France, presenting the results at the European Association for the Study of Diabetes (EASD) 2016 Annual Meeting.

She highlighted the significance of this finding for women with gestational diabetes.

"This increase in perinatal death, particularly in women with untreated gestational diabetes that we see here, is new. It is often thought that those with untreated gestational diabetes are less severe and might have lower risk of poor perinatal outcome," she said.

"It's also important to know the risk at the end of pregnancy, because the recommendation regarding induction of labor at this time is unclear."

However, Dr Jacqueminet also highlighted that it would be important to determine whether the effect seen was secondary to obesity, poor glycemic control, lack of appropriate care, and/or long-term exposure to hyperglycemia.

Chairing the session, Elisabeth Mathiesen, MD, from the University Hospital of Copenhagen, Rigshospitalet, Denmark, pointed out that the study is likely to be the first that has investigated the risk associated with gestational diabetes in pregnancy continuing beyond week 37.

"I like the way you have explored your data and presented this very clearly. We already know the risk of macrosomia and we try to manage this. The worst thing that can happen in the delivery room is the death of a baby, so I appreciate that you have looked into this," she said.

Study Examined Consistent Care, Over 1 Year

It is already known that maternal and fetal morbidity and mortality are increased in cases where diabetes exists prior to pregnancy and to a lesser extent in the case of gestational diabetes, but the exact risk level in gestational diabetes remains controversial, particularly for congenital malformations, respiratory distress, and mortality, explained Dr Jacqueminet.

Rising proportions of overweight and obese women of childbearing age mean more and more women are being diagnosed with gestational diabetes, but there is ongoing debate as to what is the ideal blood glucose "threshold" at which to diagnose it, in an attempt to balance benefits, risks, and costs of detection and treatment.

In their attempt to examine some of these issues, Dr Jacqueminet and colleagues used data drawn from the PMSI (French hospital discharge database) and the SNIIRAM (French national health insurance information system) for 2012.

Dr Jacqueminet highlighted that this is the largest cohort so far used to address gestational diabetes in France: "Many existing cohorts come from other countries. Also, studies often relate to findings over a very long period of time when care has gone through many changes, and then the outcomes are different. In our study, we looked at care over a period of 1 year so it was consistent."

They looked at all births after 28 weeks, and a further analysis was also performed for births at 37 gestational weeks or later, to address gaps in knowledge regarding the latter.

Other Findings Consistent With Other Studies

The researchers had mother-infant linked data for more than 700,000 deliveries. In terms of diabetes and treatment status, 7.24% of mothers had gestational diabetes (57,629 cases), including 16,108 treated by insulin; 0.24% had type 2 diabetes; and 0.16% had type 1 diabetes.

Other notable findings were that babies born to mothers with insulin-treated gestational diabetes showed more severe neonatal outcomes, in particular, cardiac malformation (odds ratio [OR], 1.7) and respiratory distress (OR, 1.4); figures for these outcomes in babies born to those with gestational diabetes but not treated with insulin were 1.3 and 1.1 (both comparisons were with babies born to mothers without any diabetes).

"With these findings, it is necessary to investigate whether this is attributable to unrecognized type 2 diabetes or to obesity," remarked Dr Jacqueminet.

As could be expected, the risk of macrosomia (larger-than-average baby) was doubled (OR, 2.1) in mothers with insulin-treated gestational diabetes, and for non–insulin-treated women with gestational diabetes, the OR was 1.6 (all compared with women without diabetes).

Risks of cesarean section, eclampsia/preeclampsia, and delivery at less than 37 weeks were also all increased in those with gestational diabetes and were highest in those with insulin-treated gestational diabetes.

"The data confirm the increase in maternofetal morbidity linked to gestational diabetes," say the researchers.

"The risk of perinatal death for deliveries after 37 weeks in mothers with gestational diabetes is slightly increased compared with women without diabetes," regardless of whether or not they received insulin, they reiterate

Further work is needed to investigate the reasons behind this, they conclude.

Dr Jacqueminet and coauthors have declared no relevant financial relationships.

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European Association for the Study of Diabetes 2016 Annual Meeting. September 15, 2016; Munich, Germany. Abstract 85.


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