[Effect of prolonged intravenous ritodrine tocolysis on diurnal glucose profiles in pregnant women with normal carbohydrate tolerance].

Our purpose was to investigate an effect of prolonged intravenous ritodrine tocolysis on maternal carbohydrate metabolism in women with normal glucose tolerance. In patients with preterm labor, diurnal plasma glucose levels were measured both during the 24 hours after beginning the therapy (phase 1) and each day during over five days of continuous ritodrine tocolysis (phase 2). We also measured diurnal plasma glucose levels in normal pregnant women without any therapy (control group). In phase 1, in comparison with before therapy, a significant increase in the plasma glucose levels was observed with the highest level at 9 hours after starting ritodrine (146.4 +/- 31.6mg/dl). The higher plasma glucose levels persisted during phase 1. Although infusion rates were similar in both phases, maternal plasma glucose levels in phase 1 were significantly higher than in phase 2 (mean plasma glucose level, 128.1 +/- 21.3mg/dl vs. 92.7 +/- 11.6 mg/dl, p < 0.05; maximum plasma glucose level, 159.5 +/- 25.2mg/dl vs. 106.6 +/- 14.5mg/dl, p < 0.05). Diurnal glucose levels in phase 2 were similar to those in the control group. In phase 1, there seemed to be a dose-dependent relation between the ritodrine infusion rates and plasma glucose levels, but we did not find any relationship between them in phase 2. In conclusion, although hyperglycemia occurs during the initial phase of continuous ritodrine therapy (at least 24 hours), prolonged ritodrine infusion leads to normalization of the maternal plasma glucose levels.