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MS WordPerinatologist Corner - C.E.U/C.M.E. Modules
Diabetes In Pregnancy Series
Sponsored by The Indian Health Service Clinical Support Center
PART 2: Management, delivery, and postpartum
7. Fetal Monitoring
Case continued
Ms .Kanulie returns a week later and almost all her values are in range. You make minor adjustments where necessary and compliment her on her progress. What other parameters should you be following at this time?
Fetal Monitoring
Hemoglobin A1C determinations are not sufficiently sensitive during pregnancy due to the normal physiologic plasma volume expansion and subsequent dilution effect on hemoglobin, and following them will only provide false reassurance. It is recommended that women with gestational diabetes, especially those who are insulin-dependent, should have fetal growth followed with ultrasound every four weeks.
Remember, ultrasonographic fetal weight determination formulas are subject to at least a 20% or greater error rate in the third trimester. It has been demonstrated that if fetal growth is excessive, as determined by an abdominal circumference greater than the 70th percentile, that, even in the woman with acceptable glucose values, instituting small doses of insulin may be effective in preventing the further progression of the macrosomia. (Kjos et al 2001)
Even if the patient maintains euglycemia, macrosomia may result, because there are other factors, less well understood and controllable, which determine fetal size in the diabetic woman. As noted above, there have never been any randomized controlled trials documenting the value of maintaining euglycemia with diet and insulin as regards perinatal outcome, although the data from a few cohort studies has reinforced what has become standard of care.
There are also no data from randomized trials of antepartum testing in patients with GDM, but women whose GDM is not well controlled, who need insulin (like our patient), or have other risk factors (hypertensive disease, prior poor obstetric outcome, also like our patient), are recommended to undergo testing. Many current protocols call for weekly or twice weekly non-stress testing (NST), with or without amniotic fluid (AFI) determinations after 32 weeks gestation (Kjos et al 1995), though any combination of standard methods is reasonable.
