Gestational Diabetes
Abstract & Commentary
By John C. Hobbins, MD, Professor, Department of Obstetrics and Gynecology, University of Colorado Health Sciences Center, Denver, is Associate Editor for OB/GYN Clinical Alert.
Dr. Hobbins reports no financial relationships relevant to this field of study.
Synopsis: Using California birth statistics, the authors indirectly found there was no statistically significant difference in perinatal death rate in gestational diabetes when comparing immediate delivery with expectant management until 39 weeks, when there was a higher rate of stillbirth if delivery was delayed by 1 week.
Source: Rosenstein MG, et al. The risk of stillbirth in infant death stratified by gestational age in women with gestational diabetes. Am J Obstet Gynecol 2012;206:309.e1-7
Gestational diabetes (gdm) now complicates about one in 15 pregnancies, but, undoubtedly, the prevalence will increase even further if we cannot curb the concerning rise in obesity in this country. There is ample evidence that controlling blood sugars in GDM will diminish neonatal morbidity and mortality. However, there has been no unanimity of opinion as to when to deliver well-controlled GDM patients whose fetuses show no signs of compromise.
This recent study in the American Journal of Obstetrics & Gynecology indirectly assessed the effect of a week's worth of expectant management in GDMs in late pregnancy by comparing stillbirth and infant deaths at each week of gestation from 36 to 41 weeks with perinatal deaths occurring over, and at the end of, the next week.
The authors mined information from the now often-used California Vital Birth and Death Statics data set from 1997 to 2006. Of the more than 4 million deliveries occurring during this time, 193,228 patients were labeled as having GDM. The risk of stillbirth between 36 and 39 weeks was greater in GDMs than non-diabetics (relative risk [RR] 1.45; 95% confidence interval [CI] 1.1-1.9). When comparing expectant management with immediate delivery using the method above, the risks of perinatal death were slightly lower with the former at 36 weeks, similar at 37 weeks, slightly higher at 38 weeks, and were significantly higher at 39 to 40 weeks (RR 1.8; P = 0.05).
The authors calculated that the number of GDM patients who needed to be pre-emptively delivered to prevent one perinatal death was 1518 at 39 weeks, and 1311 at 40 weeks.
Commentary
The authors admit that there were problems with their study. For example, there were no available data on the adequacy of diabetic control or the status of antenatal testing, and they did not deal with maternal or neonatal morbidity — factors that are far more common in GDM than the rare perinatal death. In fact, it took 9 years' worth of California birth statistics to unroof a significant difference in perinatal deaths (15.2 per 10,000 vs 8.7/10,000) when delivery occurred at 39 weeks, compared with 1 more week of expectant management. Before 39 weeks, there were no statistically significant differences.
For years the controversy regarding when to deliver GDMs has been all about macrosomia, shoulder dystocia, and neonatal hypoglycemia. However, using the authors' pure endpoint (death) and some interesting calculations, those taking an aggressive stance might say that GDM pregnancies should not go past 38 weeks. Those favoring the more conservative, expectant management approach would point to the need to deliver more than 1300 babies early (by 39 weeks) to avoid one perinatal death — likely at the expense of a higher cesarean section rate.
The answer is probably somewhere in between. If the patient has an unripe cervix, is in good control, and has reassuring testing, expectant management should carry an extremely small risk. However, if there is the slightest hint of trouble, then there is a suggestion from this paper that delivery at or after 38 weeks would be the most judicious course to take (just as I expect most clinicians are doing now).
Gestational diabetes (gdm) now complicates about one in 15 pregnancies, but, undoubtedly, the prevalence will increase even further if we cannot curb the concerning rise in obesity in this country.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content. TESTING
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