Title: Determining the predictive utility of short-term variation (STV) of fetal heart rate (FHR) for fetal acidaemia, and the feasibility of using this for decision making in high-risk women during labour
Funder: Department of Health and Social Care

Abstract: Background Intrapartum monitoring to assess fetal well-being has been a central component of intrapartum care for decades [23]. The National Institute for Health and Clinical Excellence (NICE) states: &ldquo;the monitoring of babies in labour aims to identify hypoxia before it is sufficient to lead to damaging acidosis and long-term neurological sequelae for the baby&rdquo; [24]. However, there is little evidence that the current use of cardiotocography (CTG) to monitor fetuses during labour has achieved this aim [2]. Despite introducing additional tests such as fetal blood sampling and analysis of fetal ECG using STAN, there has been no demonstrable improvement in perinatal outcome [2, 5, 25, 26]. Although, the antenatal use of computerised analysis of CTG, particularly short-term variation (STV) of fetal heart rate (FHR) has been assessed and shown to be beneficial in predicting acidaemia at birth [10, 27], its use during labour has not been explored in depth [12, 28, 29]. Furthermore, there is no consistent information on the STV threshold below which delivery is needed. Additionally, as previous studies only measured STV for 40 minutes or less, [30-32], it has not been possible to determine whether changes observed in STV indicated in-utero hypoxia or the effect of certain medicines known to influence FHR [33]. Our recent review [34] has stressed the need for prospective studies to measure STV for a longer time period. Aims of the work: The aim of this study is to assess the diagnostic accuracy of STV during labour to predict acidaemia at birth. Plan of investigation: We will conduct a prospective cohort study including 200 high-risk pregnant women carrying a singleton fetus, requiring continuous FHR monitoring in labour. Women will be identified from consultant led antenatal clinics at the Jessop Wing hospital, Sheffield. A description of the study and information leaflets will be provided at this visit by the attending doctor or midwife. Interested women will be consented to the study by a member of the research team either at admission to an antenatal-ward for induction of labour or to the labour-ward in established labour, at or beyond 37 completed week of gestation. The MonicaAN24 device will be fitted using disposable electrodes on the maternal abdomen. The women will remain mobile on the labour ward while the device records FHR data. Monitoring session will end when either the baby is born or after 20 hours, whichever comes first. During monitoring, clinicians will be blinded to STV and other computerized FHR parameters. However, the standard FHR patterns obtained from the MonicaAN24 will be available and will be employed for the intrapartum clinical care of the women. Midwives will be advised to press the &ldquo;event&rdquo; button on the monitor to record events, such as medicine administration, vaginal examinations etc. which have been shown to influence FHR patterns [35]. Upon completion of monitoring the device will be collected by the research team, and intrapartum FHR data will be downloaded and stored. In all cases umbilical cord will be double clamped immediately after birth and blood will be collected for analysis. Data on birth outcomes and STV will be analysed upon completion of study. Potential benefits to the patients and the NHS: Following this study, we will develop and design a definitive study to evaluate the potential place of this portable monitor in current clinical pathways. We believe that employing the specific STV threshold derived from this work, if confirmed in larger multicentre studies, would enable earlier and more appropriate interventions to expedite delivery, hence avoiding intrapartum asphyxia, brain damage and consequent disability, with a possible reduction in the incidence of medico-legal claims arising from negligent intrapartum care.

Lay abstract: During labour, babies can become distressed if oxygen levels drop and they may need urgent delivery. Currently, babies of mothers with high-risk pregnancies are continuously monitored using cardiotocography (CTG) during labour. Women having continuous CTG monitoring have to lie down, and CTG is problematic in obese women. Monitoring with continuous CTG has shown no effect on overall baby death rate or babies born with brain damage. Moving around during labour can help labour progress and reduce the need for pain relief. A lightweight portable monitor (MonicaAN24) has been developed that safely records the baby s heart-rate for up to 20 hours, regardless of the mother s weight and movement. It also records short-term variation (STV) of the heart-rate, which cannot be detected with current CTG monitors used during labour. The STV is lower in babies with low oxygen levels, so a drop in the STV number can be a sign that a baby is distressed. Currently, there is no accurate information on whether STV can reliably identify a distressed baby or on the best cut-off number of STV below which delivery is needed. In this study, 200 women will use the monitor to record the baby s STV and standard heart-rate. Decisions about care during labour will be made using the standard heart-rate data from the monitor. The STV recorded by the monitor will be downloaded after birth and analysed together with information collected about the health of the baby. In this way, we can see whether the STV match the risk of harm from low oxygen levels in labour. The results from this study will help us design a future study to test whether the STV determined by the MonicaAN24 can better identify babies at risk of harm from low oxygen levels in labour, and so offer the mother an urgent delivery.

Research activity codes: 4.2 EVALUATION OF MARKERS AND TECHNOLOGIES
Health categories: REPRODUCTIVE HEALTH AND CHILDBIRTH