Effects of prandial glycemic changes on objective fetal heart rate parameters

BACKGROUND: There is confusion in the literature about the potential effect of maternal glucose levels on the fetal heart rate (FHR) cardiotocographic interpretation. STUDY DESIGN: prospective clinical descriptive study. SUBJECTS: 21 pregnant women with diabetes mellitus, 23 women with gestational diabetes and 18 healthy non-diabetic pregnant volunteers (control group). TREATMENT: maternal capillary glucose measurement and objective FHR analysis (Oxford System 8002) pre- and 1 h post-meal. STATISTICAL ANALYSIS: descriptive statistics. Student t-tests and Pearson correlation studies. RESULTS: Maternal capillary glucose levels ranged between 2.7-10.5 mmol/l pre-meal and 4.2 14.8 mmol/l post-meal. The differences between objective FHR parameters pre- and postmeal were not significant in any of the groups of women studied. No correlation was found between prandial glycemic and FHR changes. Women with optimal and suboptimal glycemic control exhibited similar objective FHR parameters pre- and post-meal. Women with gestational diabetes showed similar prandial cardiotocographic changes irrespective of whether they were on insulin therapy or on hypoglycemic diet only. CONCLUSIONS: Objective FHR parameters are unaffected by prandial glycemic changes over a wide range of maternal glucose levels. Timing the non-stress test in relation to the meals seems irrelevant in clinical practice.