SAN DIEGO (FRONTLINE MEDICAL NEWS) – Fetal electrocardiogram ST segment analysis, or STAN, is commonly used in Europe as an adjunct to conventional intrapartum fetal heart rate monitoring, but adding STAN did not improve perinatal outcomes or decrease operative deliveries in a large, multicenter U.S. study.

Of 11,108 patients included in the 26-center study, 149 women experienced the composite primary outcome of at least one of the following: intrapartum fetal death, neonatal death, Apgar score of 3 or less at 5 minutes, neonatal seizure, cord artery pH of 7.05 or less plus base deficit of at least 12 mmol/L, intubation for ventilation at delivery, and neonatal encephalopathy, Dr. George R. Saade reported at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine.

The number of patients experiencing the composite outcome did not differ between those randomized to open or masked STAN fetal heart rate monitoring, with 79 of 5,532 in the open monitoring group (1.43%) and 70 of 5,576 in the masked monitoring group (1.26%) experiencing one or more events (relative risk, 1.14), said Dr. Saade , a professor at the University of Texas, Galveston, who presented the findings on behalf of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network in Bethesda, Md.

The open group monitors displayed relevant information used for decision making in the event of uncertain fetal heart rate patterns; the masked monitors functioned as normal monitors, he explained.

Study participants were women attempting vaginal singleton delivery at gestation of 36 weeks and 1 day or greater with cervical dilation of 2-7 cm between November 2010 and March 2014. The open and masked STAN monitoring groups did not differ with respect to baseline characteristics or with respect to parity, type of labor, cervical dilation at study entry, and study period.

The groups also did not differ in secondary study outcomes, including the type of delivery and measures of morbidity.

For example, operative vaginal delivery occurred in 5.9% of patients in both groups (relative risk, 1.02), and cesarean delivery occurred in 16.9% and 16.2% of the open and masked group patients, respectively (RR, 1.05). Additionally, intermediate/NICU stay was required in 9.0% and 8.4% of patients in the groups, respectively (RR, 1.07), meconium aspiration occurred in 0.4% of patients of both groups (RR, 1.01), and shoulder dystocia occurred in 2.5% and 2.8% (RR, 0.90).

All participating providers were trained and certified per approved management guidelines for STAN, and a training pilot study involving 1,527 women from 31 centers was conducted at each site prior to the randomized controlled trial.

“This is the largest fetal ECG randomized trial conducted to date, with the highest rate of available cord gasses. We feel that our study is more applicable to U.S. practice than [are] all other prior studies,” Dr. Saade said, concluding that the validity of the results is strengthened by the “intensive training and rigorous certification,” of providers, as well as by the inclusion of real-time review feedback after training, central review of outcomes, and the use of an independent data coordinating center.

Many community and university hospitals were represented in the study, as were a variety of providers – including residents and midwives – and types of practices.

Even in subgroup analyses, and after controlling for site of service, there were no differences in outcomes observed between the study groups. This suggests that the findings are generalizable across the United States, Dr. Saade said.

When asked why European studies have shown a benefit with STAN monitoring, Dr. Saade said that the main difference seen in systematic reviews was a lower rate of fetal scalp sampling with STAN monitoring. “In the United States, we don’t do fetal scalp sampling, so that won’t help us here,” he said.

Dr. Saade reported having no financial disclosures.