Reader raises a question about article on stillbirth

April 1, 2010

In the article, glycosylated hemoglobin is described as, at best, of uncertain utility.

I read with interest the article about stillbirth (Silver RM. Contemporary Ob/Gyn. 2009;54[12]:35-43). In the article, glycosylated hemoglobin is described as, at best, of uncertain utility.

In an obese woman who had a normal 1-hour glucola at 28 weeks and a 39-week stillbirth weighing >5,000 g, what testing would Dr Silver do? Would he recommend a glycosylated hemoglobin or fasting blood sugar? If the glycosylated hemoglobin were in the normal range, the fasting blood sugar 150, and all other testing, including autopsy, negative, would he ascribe the cause to late-onset gestational diabetes?

Russel D Jelsema, MDGrand Rapids, Michigan

I appreciate Dr Jelsema's interest in the article regarding stillbirth in Contemporary Ob/Gyn. He raises the question of whether it is appropriate to consider glycosylated hemoglobin as a test of uncertain clinical utility.

As an example, he proposes a case that raises suspicion for gestational (or pregestational) diabetes involving an obese woman delivering a macrosomic fetus at term. She has a normal 1-hour glucola screen, a normal glycosylated hemoglobin, and an elevated fasting blood sugar.

I agree with Dr Jelsema that a screen for glycosylated hemoglobin is potentially helpful in this case. My intent in the article was to recommend against testing for glycosylated hemoglobin in every case of stillbirth as part of a comprehensive panel.

Although there is some evidence that subclinical glucose intolerance may be a risk factor for stillbirth, the vast majority of women with subclinical glucose intolerance do not have stillbirths. Thus, widespread screening would be considered experimental.

It is appropriate and recommended that glycosylated hemoglobin (or another assay for diabetes) be performed in all cases with clinical suspicion for diabetes, such as in the hypothetical case presented. The same is true for many tests that could potentially identify important but relatively uncommon risk factors or causes of stillbirth or conditions that are almost always associated with clinical or pathologic evidence of the condition.

I would consider the case in question to be a possible cause of stillbirth. The mother has a large-for-gestational-age fetus and evidence of pregestational diabetes, likely type 2. There are numerous classification systems that catalog causes of stillbirth and, in some systems, this case would be classified as being due to diabetes.

In my experience, it is extremely unlikely that someone would have a markedly elevated fasting blood sugar with normal glycosylated hemoglobin. Regardless, attention to glycemic control in subsequent pregnancies seems prudent in this case.

Thanks again to Dr Jelsema for raising an important question and providing me with an opportunity to clarify my recommendations. Hopefully, further studies including analysis of data from the Stillbirth Collaborative Research Network will help to refine the optimal use of diabetes screening and testing as part of the evaluation of stillbirth.

Robert M Silver, MDSalt Lake City, Utah