The benefits of concurrent fetal and maternal heart rate monitoring

Neonatal encephalopathy and severe neonatal acidemia rates are increased by external ultrasound transducer (US) monitoring of fetal heart rate (FHR) when not utilizing maternal heart rate (MHR) recording, according to a recent study published in the American Journal of Obstetrics & Gynecology.

Cardiotocography (CTG) is the most common fetal surveillance method used during labor, evaluating uterine activity and FHR trends. Simultaneous MHR monitoring is also available with new-generation CTG. This method provides a noninvasive monitoring approach without requiring extra transducers.

Recent data has indicated increased perinatal death risk among patients using FHR monitoring with US alone. As maternal pulse may obscure FHR patterns, there is a need to investigate simultaneous monitoring of MHR and intrapartum FHR.

Investigators conducted a study determine the association between fetal surveillance method and adverse perinatal outcome risk. Data was obtained from the Hospital District of Helsinki and Uusimaa (HUS), Finland, and included intrapartum GTG recordings, clinical delivery-related data, umbilical artery (UA) results, and neonatal intensive care unit (NICU) treatment data.

Participants included women in the active stage of labor with regular uterine contractions and spontaneous cephalic delivery receiving continuous CTG monitoring. Exclusion criteria included preterm pregnancy, cesarean, instrumental, and breech deliveries, twins, maternal blood-borne contagious diseases, and major congenital malformations.

Electronic obstetrical patient records were evaluated to obtain clinical data. UA blood gas results were collected from the HUS Weblab Clinical laboratory information system (HUS, Helsinki, Finland). Electronic medical records were assessed for NICU admission, resuscitation, and neonatal encephalopathy data.

Base excess (BE) of −12.0 mmol/L or less in UA blood or pH below 7, Apgar score under 7 at 5 minutes, intubation for resuscitation at delivery, neonatal encephalopathy, early neonatal death, and composite neonatal asphyxia outcome were the primary outcomes of the analysis. Secondary outcomes included statistically defined UA pH limit and NICU admission for asphyxia.

There were 213,798 deliveries included in the final analysis, 38.1% of which received US alone, 29.1% US and MHR, and 32.7% fetal scalp electrode (FSE). The risk of neonatal encephalopathy was increased 1.7-fold in deliveries with US alone vs US and MHR or FSE.

Other risks increased by US alone vs US and MHR or FSE included UA pH under 7, UA BE of −12.0 mmol/L or less, and 5-minute Apgar score under 7, with odds ratios of 2.16, 2.37, and 1.22, respectively. Additionally, composite neonatal asphyxia risk was increased 1.3-fold.

Neonatal encephalopathy, UA pH under 7, and UT BE of −12.0 mmol/L or less risks were increased 1.5-fold, 2-fold, and 2-fold, respectively, for US alone vs US and MHR. Neonatal intubation for resuscitation and NICU admission risks were also increased by US alone vs US and MHR.

When compared to FSE monitoring, the risks of neonatal encephalopathy, severe neonatal acidemia, and 5-minute Apgar scores under 7 were increased 2-fold, 2.4- to 2.8-fold, and 1.2-fold, respectively, among fetuses with US alone. Similar outcomes were reported for neonatal intubation for resuscitation and NICU admission.

For secondary outcomes, the risk of moderate acidemia was increased 2- to 2.1-fold among newborns of mothers with US alone vs those with US and MHR or FSE. Additionally, the risk of NICU admission for neonatal asphyxia was increased 1.3-fold among these patients.

These results indicated significantly improved outcomes when using concurrent intrapartum MHR monitoring during FHR monitoring. Investigators recommended concurrent MHR recording or FSE be utilized during labor in term pregnancies.

Reference

Tarvonen M, Markkanen J, Tuppurainen V, Jernman R, Stefanovic V, Andersson S. Intrapartum cardiotocography with simultaneous maternal heart rate registration improves neonatal outcome. Am J Obstet Gynecol. 2024;230:379.e1-12. doi:10.1016/j.ajog.2024.01.011