Gestational diabetes is associated with an increased risk of congenital malformity

An image of a foetus

Clinical question

Is gestational diabetes associated with congenital malformities?

Having diabetes is associated with a greater risk of malformation at birth.  This systematic review looked at whether gestational diabetes is also associated with an increase in risk.

The evidence

The reviewers found 17 studies that reported malformities in the children of women with gestational diabetes compared to women without.

When they combined all the dat from these studies, gestational diabetes was associated with a statistically significant increase in the risk of malformity.  The relative risk was 1.16, or a 16% increase in risk compared with women without diabetes.

Women with diabetes that existed before they got pregnant were seen to have more than double the risk of malformity compared with non-diabetic women.

Appraisal hints

Users of this research are advised to consider:

  • Whether the patient population is similar to those in which this evidence would be applied.
  • Look for subgroup analysis for different patient groups (e.g. stratified by glycaemic control, demographics).
  • Did the reviewers do enough to find and include all of the best quality studies?
  • Whether the reviewers only included good quality studies, or what the effects of any potential bias might be.
  • Whether the increase in risk might be caused by other factors.
  • Whether it made sense to combine all of the studies in one overall result.
  • The baseline risk of malformities and what the absolute risk increase would be for a particular patient or population.


Montserrat B, Apolonia GP et al. Major congenital malformations in women with gestational diabetes mellitus: A systematic review and meta-analysis.  Diabetes Metab Res Rev. 2011 Nov 3. doi: 10.1002/dmrr.1304. [Epub ahead of print]


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I am an information scientist with an interest in making knowledge from systematic research more accessible to people who need it. This means you. I've been attempting this in the area of Evidence-Based Health Care since 1995. So far the results have been mixed. For some reason we expected busy clinicians to search databases and appraise papers instead of seeing patients. We also expected publishers to make the research freely available to the people who paid for it.. Ha! Hence The National Elf service.

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