Labour · Fetal Monitoring
CTG / Electronic Fetal Monitoring
What CTG (cardiotocograph) monitoring shows about your baby in labour. The 4 features (baseline, variability, accelerations, decelerations), Normal / Non-reassuring / Pathological categories, when continuous is needed, alternatives, and what fetal blood sampling means. NICE NG201 / FIGO.
Last reviewed 2 June 2026
NICHD CTG categorisation
Intrapartum fetal heart trace — I / II / III
Baseline (bpm)
Variability
Accelerations
Decelerations
Select all four CTG features to categorise.
Educational tool only — not medical advice. Macones 2008 NIH workshop / ACOG PB 229 (2010, reaffirmed 2021). Category III is uncommon but predictive of abnormal fetal acid-base status. The MAJORITY of intrapartum CTGs are Category II — a heterogeneous group requiring clinical judgement and serial reassessment.
What does this mean?
The NICHD CTG categorisation (Macones 2008 / ACOG PB 229) groups intrapartum fetal heart rate tracings into three buckets. Category I: completely normal — strongly predictive of normal fetal acid-base; routine care. Category III (sinusoidal pattern OR absent variability + late/variable decels or bradycardia): predictive of abnormal acid-base; expedite delivery, intrauterine resuscitation NOW (position change, IV fluid bolus, oxygen, stop oxytocin, treat hyperstimulation). The catch: most intrapartum tracings are Category II — everything that isn’t Cat I or III — a heterogeneous bag requiring clinical judgement, serial reassessment, and a low threshold for fetal scalp blood sampling, fetal scalp stimulation, or proceeding to delivery if not progressing. Cochrane reviews show continuous EFM increases C-section rate without clear long-term benefit in low-risk labour vs intermittent auscultation — so risk-stratify who needs it.
What is CTG?
Cardiotocograph — also called EFM. Continuously records baby’s heart rate and your contractions. Two straps around bump; print-out shows pattern over time.
Who needs continuous CTG?
NICE NG201 / RCOG continuous CTG indications:
- VBAC (previous C-section).
- Meconium in liquor.
- Oxytocin augmentation.
- Induction of labour.
- Pre-eclampsia.
- Growth restriction (IUGR).
- Multiple pregnancy.
- Breech.
- Preterm.
- Maternal sepsis.
Low-risk labour: intermittent auscultation preferred (less restrictive).
The 4 features
- Baseline rate: 110-160 bpm normal.
- Variability: 5-25 bpm normal.
- Accelerations: rises ≥15 bpm for ≥15 sec — reassuring.
- Decelerations: drops — type matters (see below).
Categories
- Normal: all reassuring.
- Non-reassuring: one abnormal feature.
- Abnormal: ≥2 abnormal.
- Pathological: severe — needs immediate action.
Decelerations explained
- Early: mirror contraction; head compression; usually benign.
- Late: start after contraction peak, slow recovery; placental insufficiency.
- Variable: V-shaped; cord compression.
- Prolonged: >2 min; urgent assessment.
If non-reassuring
- Check / reduce contractions.
- Maternal position change (left lateral).
- IV fluids.
- Oxygen sometimes.
- Stop oxytocin if running.
- Scalp stimulation.
- Fetal blood sample (pH check).
- Senior review.
Fetal blood sampling (FBS)
- pH ≥7.25: reassuring.
- pH 7.20-7.25: borderline.
- pH <7.20: acidotic — expedited delivery.
Mobility in labour
Wired CTG restricts movement. Wireless / telemetry (Monica, Novii, MOYO) increasingly available — allows mobility + pool labour. Check unit availability; specify in birth plan.
Can I refuse continuous CTG?
Yes — informed choice. Intermittent auscultation is the NICE-supported alternative for low-risk labour. Discuss risks if high-risk.
Different scenarios
Scenario 1: Low-risk labour, healthy pregnancy
Intermittent auscultation (handheld Doppler every 15 min). No continuous CTG.
Scenario 2: VBAC labour
Continuous CTG required. Wireless monitor for mobility if available.
Scenario 3: Non-reassuring trace at 6 cm dilated
Position change, IV fluids, scalp stimulation. Fetal blood sample if persists. Possible expedited delivery.
Scenario 4: Pathological trace with prolonged deceleration
Emergency. Category 1 C-section within 30 minutes. Theatre transfer.
Scenario 5: Post-dates 41 wk CTG
30-40 min antenatal CTG. Reactive trace reassuring. Plan induction discussion.
Care guidance — CTG
- Continuous CTG when indicated; intermittent low-risk.
- Wireless / telemetry where available.
- Position changes during monitoring.
- Ask midwife to explain trace if you want.
- Discuss in birth plan.
- Informed choice to decline (low-risk).
Sources
- NICE NG201 / NG235. Intrapartum care.
- FIGO. Consensus guidelines on intrapartum fetal monitoring.
- RCOG. Each Baby Counts national programme.
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Frequently asked questions
What is CTG monitoring?
CTG (CARDIOTOCOGRAPH) — also called EFM (electronic fetal monitoring). Continuously records baby's HEART RATE and your CONTRACTIONS during labour (or pregnancy if monitoring). TWO STRAPS around your bump: one detects baby's heartbeat (Doppler ultrasound); one detects contractions (pressure sensor). PRINT-OUT or screen shows pattern over time. USED to identify babies who might be struggling. UK NHS standard for high-risk labours + selected antenatal monitoring.
Who needs continuous CTG in labour?
NICE NG201 / RCOG: CONTINUOUS CTG recommended if: PREVIOUS C-SECTION (VBAC); MECONIUM in liquor; OXYTOCIN augmentation; INDUCTION; PRE-ECLAMPSIA; GROWTH RESTRICTION (IUGR); MULTIPLE pregnancy; BREECH; PRETERM (32+ weeks where vaginal birth attempted); previous concerns; maternal sepsis; antepartum haemorrhage. LOW-RISK labour: INTERMITTENT AUSCULTATION with handheld Doppler is preferred (every 15 min in 1st stage, every 5 min in 2nd) — less restrictive, allows mobility.
How is CTG categorised?
FIGO / NICE 4 FEATURES assessed: (1) BASELINE rate (normal 110-160 bpm); (2) VARIABILITY (5-25 bpm normal); (3) ACCELERATIONS (heart rate rises ≥15 bpm for ≥15 sec — REASSURING); (4) DECELERATIONS (heart rate drops). PATTERNS: NORMAL (all reassuring); NON-REASSURING (one abnormal feature); ABNORMAL (≥2 abnormal features); PATHOLOGICAL (severe abnormal — needs immediate action). DECISIONS based on overall pattern + clinical context.
What's a normal baseline heart rate?
110-160 bpm at term. PRETERM babies tend to be at upper end. WHAT'S NORMAL: gradual changes; episodic accelerations during movement; mild decelerations correlated with contractions can be normal. TACHYCARDIA (>160 sustained): infection, maternal fever, dehydration, drug effects, baby distress. BRADYCARDIA (<110 sustained): vagal stimulation, cord compression, severe hypoxia — needs urgent assessment.
What are accelerations and decelerations?
ACCELERATIONS: brief rises in heart rate ≥15 bpm above baseline for ≥15 sec. POSITIVE sign — baby active + well-oxygenated. AT LEAST 2 in 20 minutes = reactive (reassuring). DECELERATIONS: drops in heart rate. EARLY (mirror contraction, return to baseline) — physiological, head compression usually. LATE (start after contraction peak, slow recovery) — placental insufficiency. VARIABLE (V-shaped, irregular timing) — cord compression. PROLONGED (>2 min) — needs urgent assessment + delivery if persistent.
What does 'pathological CTG' mean?
SERIOUS CONCERN — severe abnormal features. INDICATIONS for URGENT ACTION: PROLONGED DECELERATION >3-5 min; LATE decelerations with reduced variability; ABSENT variability >40 min; SUSTAINED bradycardia or tachycardia. ACTIONS: (1) Stop oxytocin if running; (2) Maternal position change (left lateral); (3) IV fluids bolus; (4) Oxygen sometimes; (5) FETAL SCALP STIMULATION (if cervix dilated — accelerations after = reassuring); (6) FETAL BLOOD SAMPLING if available; (7) EXPEDITED DELIVERY — vaginal if quick + safe; C-section if not. CATEGORY 1 ('crash') C-section: birth within 30 minutes.
Why are continuous CTGs sometimes problematic?
CTG associated with: INCREASED C-SECTION RATE (without clear improvement in cerebral palsy rates in low-risk women) — Cochrane review found this. RESTRICTS MOBILITY (straps around bump, sometimes wired to monitor). CAN MISS CONTEXT — over-interpretation of mild abnormalities. ANXIETY for parents watching the trace. WIRELESS / waterproof monitors increasingly available — allow movement + pool labour. BALANCED approach: continuous for high-risk; intermittent auscultation low-risk.
What if my CTG is non-reassuring?
ESCALATED MONITORING + interventions: (1) CHECK contractions (excessive can cause distress); (2) MATERNAL POSITION change; (3) IV fluids; (4) OXYGEN; (5) STOP oxytocin if running; (6) SCALP STIMULATION; (7) FETAL BLOOD SAMPLE (FBS) — checks pH from scalp blood; pH ≥7.25 reassuring, <7.20 needs delivery; (8) SECOND OPINION from senior obstetrician/midwife. IMPROVEMENT often happens — labour can continue. NO IMPROVEMENT: expedited delivery.
Will continuous CTG affect my birth experience?
CAN — restricts mobility (straps, wired monitor). REQUEST wireless / telemetry CTG if available — most UK units now have. ALLOWS pool labour (waterproof versions), walking, position changes. DISCUSS in birth plan. WIRED CTG: can still change positions in bed; turn left; ankle / knee bends; pelvic rocking. EPIDURAL: doesn't affect CTG monitoring. ASK midwife to explain trace if you want to follow.
Can I refuse continuous CTG?
YES — informed choice. IF LOW-RISK labour, intermittent auscultation is standard alternative + NICE-supported. IF HIGH-RISK (VBAC, IOL, etc.), discuss risks of declining — increased risk of missing fetal distress. WRITTEN documentation. INFORMED consent process. SOME WOMEN compromise: intermittent monitoring with handheld Doppler instead of continuous CTG, accepting some monitoring.
What's fetal blood sampling (FBS)?
When CTG is non-reassuring, can take SMALL blood sample from baby's scalp (presenting in cervix). MEASURES pH (acid level — indicates oxygen delivery). pH ≥7.25: reassuring; pH 7.20-7.25: borderline (repeat in 30 min); pH <7.20: acidotic, expedited delivery. PROCEDURE: speculum exam during labour; small lancet pricks scalp; few drops on test strip. SOME DISCOMFORT for baby (transient). NOT all units offer; STAN (ST-analysis) sometimes used instead.
What if my baby has variable decelerations?
USUALLY CORD COMPRESSION. Common during pushing stage. Can be benign if: brief; quick recovery; good variability between; baseline maintained. CONCERNING if: deep (>60 bpm drop or >60 sec); slow recovery; reduced variability between; baseline changes. POSITION CHANGE often helps (relieves cord pressure). AMNIOINFUSION sometimes used in preterm with low fluid. CLINICAL JUDGMENT important.
What about post-dates / antenatal CTG?
POST-DATES (≥41 wk) ASSESSMENT: 30-40 min CTG to check baby OK. REDUCED FETAL MOVEMENTS: same. ANTENATAL CTG: 20-30 min usually. CRITERIA for normal: ≥2 accelerations in 20 min; normal baseline; normal variability; no concerning decelerations. NON-REACTIVE: extend or follow with ultrasound (BPP/Doppler). PROVIDES reassurance OR identifies babies needing delivery.
Can wireless CTG / telemetry monitor be used?
INCREASINGLY available UK. ADVANTAGES: mobility; pool labour possible; less restrictive; better positions for labour. EXAMPLES: Monica AN24, Novii, MOYO. SAFETY: equivalent to wired CTG. ASK YOUR UNIT — availability varies; check during pregnancy. PREFERENCE in birth plan.
How does this relate to other calculators on BumpBites?
Companion: /calculators/kick-counter for movement monitoring; /calculators/biophysical-profile; /calculators/birth-plan-builder; /calculators/vbac-success; /calculators/bishop-score; /calculators/membrane-sweep.