The effect of maternal glucose administration on the specificity of the nonstress test. Non-stress antenatal cardiotocography--a prospective randomized clinical trial.
To determine whether maternal glucose administration can decrease the incidence of false positive nonstress tests, 296 nonstress tests were performed on 235 high-risk obstetric patients in a prospective controlled study. Patients were alternately given a 50 gm oral glucose drink or an equal volume of water 30 minutes prior to the commencement of each test. Among "fed" patients (last meal within 2 hour of the nonstress test) whether receiving glucose or water, and "fasted" patients who received glucose, there was no significant difference in the percentage of reactive tests at either 20 minutes (65.2%) or 40 minutes (87.3%) of testing. However, patients fasting and receiving water had a significantly decreased percentage of reactive tests, both at 20 minutes (48.3%, P less than 0.01) and at 40 minutes (76.7%, P less than 0.05). Glucose administered to fasted patients resulted in an increase in the incidence of reactive tests, although this was not statistically significant. Glucose administration had no effect on the nonstress test results when administered to fed patients. A randomized controlled trial examined the effects of non-stress antepartum cardiotocography on obstetric management and assessed its usefulness as a diagnostic test of fetal compromise. Daily cardiotocograph recordings were made in 396 antenatal patients at increased risk of fetal compromise but were withheld from the clinicians responsible for care in half the cases. The frequency of intrapartum fetal distress and low Apgar score was similar in the two groups. The three normally-formed perinatal deaths all occurred in the revealed group but in only one case could earlier obstetric intervention have altered the outcome. Availability of non-stress cardiotocography was not associated with an increased rate of induction of labour or caesarean section.
Antenatal maternal glucose administration has not been shown to reduce non-reactive cardiotocography. More trials are needed to further substantiate this and to determine not only the optimum dose, but also to evaluate the efficacy, predictive reliability, safety and perinatal outcome of glucose administration in conjunction with cardiotocography and also other tests of fetal wellbeing.