Fetal Monitoring and CTG in Labour

Two methods, one decision

NICE's fetal monitoring guideline (NG229) sets out two approaches. Intermittent auscultation means listening to your baby's heart at intervals with a Pinard stethoscope or a handheld doppler. Continuous cardiotocography, or CTG, means two pads strapped to your bump — one recording the baby's heartbeat, one recording contractions — producing a continuous trace.

NICE offers intermittent auscultation to "women with a low risk of complications ... when in established first stage of labour". Continuous CTG is offered "as part of fetal assessment if any antenatal or intrapartum risk factors for fetal compromise are present."

The guideline is unusually candid about the downside of monitoring everyone. Teams should explain that where there are no identified risk factors, "there is a risk of increased interventions with continuous CTG monitoring compared with intermittent auscultation, which may outweigh the benefits."

And it is equally clear about what a CTG is not: "fetal heart rate monitoring is a tool to provide guidance on fetal condition, and not a standalone diagnostic tool", and "the findings from monitoring need to be looked at together with the developing clinical picture for both woman and baby."

How intermittent listening works

NICE specifies the technique precisely. In the established first stage: listen "immediately after a palpated contraction for at least 1 minute, repeated at least once every 15 minutes", record it as a single rate, note any accelerations or decelerations, and palpate your pulse hourly to make sure the midwife is not counting your heartbeat rather than the baby's.

In the second stage the frequency increases: "immediately after a palpated contraction for at least 1 minute, repeated at least once every 5 minutes", with your pulse palpated at the same time. NICE warns that "it is particularly important to confirm the fetal heart rate in the second stage of labour, when it is easier to mistakenly auscultate maternal rather than fetal heart rate."

The NHS describes what this feels like: "a small handheld device to listen to your baby's heart every 15 minutes. You'll be free to move around as much as you want."

What would change it

NICE gives a specific trigger: if the fetal heart rate rises "20 beats a minute or more from the start of labour, or a deceleration is heard", listening becomes more frequent, for example after three consecutive contractions, and a full clinical review follows. If concerns are confirmed, continuous CTG is advised and — in a midwifery-led setting — transfer to obstetric-led care is arranged.

Importantly, this can be reversed. NICE says to "return to intermittent auscultation if continuous CTG monitoring has been started because of concerns arising from intermittent auscultation but the CTG trace is normal after 20 minutes, unless the woman decides to remain on continuous CTG monitoring."

What puts you on continuous CTG

NICE lists antenatal maternal risk factors including a previous caesarean birth or other full thickness uterine scar; any hypertensive disorder needing medication; prolonged ruptured membranes; any vaginal blood loss other than a show; suspected chorioamnionitis or maternal sepsis; and pre-existing diabetes or gestational diabetes requiring medication.

Antenatal fetal risk factors include non-cephalic presentation such as breech, transverse or oblique; fetal growth restriction; small for gestational age with other high-risk features; more than 42+0 weeks at the onset of established labour; anhydramnios or polyhydramnios; and reduced fetal movements in the 24 hours before regular contractions began.

Intrapartum risk factors that develop during labour include contractions lasting longer than two minutes or five or more contractions in ten minutes; the presence of meconium; maternal pyrexia defined as "a temperature of 38°C or above on a single reading or 37.5°C or above on 2 consecutive occasions 1 hour apart"; suspected chorioamnionitis or sepsis; and pain that you describe as different from normal contraction pain.

The NHS adds the two most common practical reasons: an epidural, and an oxytocin drip to speed up labour. It also notes you can ask for electronic monitoring even if there are no concerns.

How a trace is read

NICE asks clinicians to assess and document five things on every review: contractions, baseline fetal heart rate, variability, the presence or absence of decelerations and their characteristics, and the presence of accelerations.

Baseline is the mean heart rate over a stable ten-minute stretch, excluding accelerations and decelerations. NICE grades it white for "a stable baseline of 110 to 160 beats a minute"; amber for a rise of 20 beats a minute or more since labour started or since the last review, or a rate of 100 to 109, or being unable to determine a baseline; and red for below 100 or above 160.

Variability is the minor oscillation in the trace, measured between contractions. Five to 25 beats a minute is graded white. NICE flags absent variability as "a very concerning feature" warranting a review of the whole clinical picture "with a low threshold for expedited birth".

The four features are then combined. NICE categorises the overall trace as normal when there are "no amber or red features"; suspicious when "any 1 feature is amber"; and pathological when "any 1 feature is red, or 2 or more features are amber."

NICE is careful about what those words mean: categorisation "is a tool which quickly communicates the current state of the CTG and should be used together with antenatal and intrapartum risk factors, to assess changes over time." A suspicious trace is a prompt to look harder, not a diagnosis.

Fresh eyes and hourly review

NICE requires a full assessment of you and your baby every hour, covering maternal and fetal antenatal risk factors, new or developing intrapartum risk factors, progress in labour, and changes to the heart rate pattern. Changes should be discussed with you.

For women on CTG there is a second layer: "obtain an in-person review of every hourly assessment by another clinician ('fresh eyes') ... to be completed before the next assessment takes place." If someone you have not met appears to look at the trace, that is why.

Moving while monitored

NICE tells teams to "encourage and help women to be as mobile as possible, to find positions that are comfortable for them, and to change position as often as they wish", even on continuous CTG. It also asks that wireless transducers be "kept charged and maintained so that they are ready to use".

Be aware of the honest caveat NICE asks teams to give: continuous CTG "may restrict her mobility and the option to labour in water." Telemetry helps but is not universally available.

Scalp electrodes

If the trace quality is poor, a fetal scalp electrode attached to the baby's head may be suggested. The NHS says this "can give a more accurate measurement of your baby's heartbeat" and that it "will usually only be removed just as your baby is born, not before."

What you can ask for

NG229 opens with information and decision-making, not technology. Teams should discuss monitoring options antenatally and document them in your personalised care plan; confirm with you in labour which method has already been advised; explain the method being recommended and why; support your decision; and keep you and your birth companions "informed about what is happening if additional advice or review is being sought by the care team".

NICE also asks teams to explain that "risk assessment is a continual process, and the advised method of fetal heart rate monitoring may change throughout the course of labour" — in either direction.