Table 1 Currently available fetoplacental monitoring tools with strengths and limitations

sFLT1:PLGF

Easy to perform, a cut off value > 38 has a predicts pre-eclampsia.

Only validated after 20 weeks’ gestation (therefore too late to implement early aspirin use).

CTG

Antenatal

The use of Dawes Redman criteria allows for non-subjective analysis with strong evidence of STV < 4 indicating fetal hypoxia and acidaemia.

Intrapartum

Allows for continuous and real time monitoring of fetal heart rate and uterine contractions. Reduces the risk of neonatal seizures by half compared to intermittent auscultation. Allows early recognition of rapid fetal wellbeing deterioration in acute events such as cord prolapse and placental abruption, identifying babies requiring urgent delivery.

Both resource and training dependent. Obstetric units using CTG both antenatally and intrapartum need to have the ability to provide regular training for staff on context specific interpretation and escalation of CTG.

Intrapartum

A high degree of subjectivity and susceptibility to operator misinterpretation. Does not reduce the risk of perinatal death or cerebral palsy, but increases the rate of cesarean section and operative vaginal delivery.

Growth charts

Few resources are required, scalable to all resource settings.

Population charts may not be applicable in highly heterogeneous populations, and customised charts do not reduce the incidence of SGA and may disproportionately. disadvantage women from ethnic minority background.

Fetal Doppler

Use of UA Doppler in the assessment of high-risk patients reduce risk of perinatal death., use of DV Doppler in early growth restriction is a good predictor of fetal compromise and reduces the risk of subsequent neonatal neurological deficits.

Highly operator and resource-dependent, inter-operator variability is a concern.

Fetal movements

Reduced and lack of movements correlate with poor outcomes (such as stillbirth and hypoxia).

Progress being made towards optimising wearable fetal movement monitors.

Highly subjective, can cause maternal anxiety and repeated attendances to maternity services, relies on patient understanding of fetal movements and ability to access services, currently no clear package of care with demonstrated improvement in outcomes for RFM.

Current commercial wearable fetal movement monitors are susceptible to noise and maternal movement artefacts.