CTG Test in Pregnancy: What It Measures and How to Read It

A CTG test is a non-invasive monitoring procedure that records two signals simultaneously: the fetal heart rate and the pattern of uterine contractions. CTG stands for cardiotocography, cardio referring to the heart, toco referring to uterine contractions, and graphy meaning recording.

CTG testing is ordered when a clinician wants objective reassurance about fetal wellbeing, either because a risk factor is present, a symptom has been reported, or labour is in progress.

High-risk pregnancy, gestational diabetes, hypertension, preeclampsia, intrauterine growth restriction, and post-dates pregnancy are among the conditions that indicate closer fetal monitoring.

Reduced fetal movement, when a pregnant woman reports that movement has decreased from her established pattern, CTG provides an immediate assessment of fetal heart rate reactivity.

Labour monitoring, during induced labour, augmented labour, or labour following an epidural, continuous CTG monitoring is standard practice in most hospital settings.

Multiple pregnancy, twin and higher-order pregnancies require closer surveillance as placental sharing and positional factors increase risk.

Previous obstetric complications, a history of stillbirth, growth restriction, or placental insufficiency in a prior pregnancy increases monitoring frequency.

Maternal health conditions, kidney disease, cardiac conditions, or infections that may compromise placental function are indications for increased fetal surveillance.

The CTG trace consists of two separate graphs recorded on a single strip. Each reflects a distinct physiological signal.

Fetal Heart Rate (FHR)

The upper trace records the fetal heart rate in beats per minute. A normal resting fetal heart rate sits between 110 and 160 bpm. Four elements are assessed within the fetal heart rate trace:

Baseline rate, the average heart rate sustained over a ten-minute period, excluding accelerations and decelerations. Values below 110 bpm (bradycardia) or above 160 bpm (tachycardia) fall outside the normal range.

Variability, the natural beat-to-beat fluctuation around the baseline. A healthy, alert fetus shows variability of 5–25 bpm. Reduced variability, less than 5 bpm sustained over 40 minutes, may indicate fetal sleep, but can also reflect compromise in certain contexts.

Accelerations, transient increases in fetal heart rate of at least 15 bpm above baseline, lasting at least 15 seconds. Two or more accelerations within a 20-minute window is a reassuring sign of fetal wellbeing.

Decelerations, transient drops in fetal heart rate below baseline. Early decelerations that correspond in timing with contractions are generally benign. Late decelerations, those that begin after the contraction peak, and variable decelerations may indicate cord compression or reduced uteroplacental oxygen transfer.

Uterine Contractions

The lower trace records uterine activity. Each upward curve represents a contraction, the height reflects intensity and the width reflects duration. During active labour, contractions are expected and the trace shows regular peaks.

Outside of labour, this line remains relatively flat. The contraction trace is interpreted alongside the fetal heart rate trace to determine whether decelerations are occurring in a pattern that corresponds to uterine activity.

The procedure is conducted with the patient lying in a semi-reclined or left-lateral position, positioning that optimises sensor contact and avoids aortocaval compression from the weight of the uterus.

Two sensor belts are secured around the abdomen. The ultrasound transducer is positioned over the area of strongest fetal heart signal, which the clinician locates using the audible heartbeat.

The tocometer is placed over the uterine fundus, the uppermost part of the uterus, where contraction activity is most reliably detected.

CTG interpretation requires all four fetal heart rate features to be assessed together. No single feature is interpreted in isolation, a trace is classified as reassuring, non-reassuring, or abnormal based on the combination of findings.

A reactive trace, the reassuring classification, shows a normal baseline, adequate variability, two or more accelerations, and no significant decelerations. A non-reassuring or abnormal trace prompts further clinical assessment rather than an immediate intervention decision.

For working women in the second and third trimesters, attending antenatal monitoring appointments during working hours creates a recurring access challenge, particularly in urban settings where hospital waiting times can extend a routine CTG assessment into a half-day absence.

Diagnostics and Monitoring, 8,500+ NABL-Accredited Labs and Clinics Visit Health's diagnostic network includes antenatal monitoring access across India. Employees can book appointments cashlessly through the app, with results tracked digitally and accessible without physical report collection.

Teleconsultation, Obstetrics and Gynaecology When a CTG trace result raises questions or a follow-up specialist opinion is needed, Visit Health's teleconsultation platform connects employees with obstetricians and gynaecologists across 30+ specialties, same day, without requiring a hospital visit or a separate referral queue.

AI-Powered Smart Reports CTG traces are interpreted by clinicians, but for patients who want to understand what their monitoring report means before a follow-up appointment, Visit Health's Smart Reports provide plain-language summaries of antenatal findings and what the recommended next step is.

Visit Clinic, Bengaluru (Marathahalli, Outer Ring Road) For employees in Bengaluru who need an in-person obstetric consultation or antenatal assessment, Visit Clinic provides on-ground appointments during standard working hours, connected into the broader specialist ecosystem.

A CTG test provides clinicians with real-time information about fetal wellbeing, specifically how the fetal heart is responding to the uterine environment and to contractions. Understanding what the four key features of a CTG trace represent, and how they are interpreted together rather than individually, enables a more informed and less anxious experience during monitoring.

What does CTG stand for in pregnancy?

Cardiotocography. It records the fetal heart rate and uterine contractions simultaneously using external sensors placed on the abdomen.

Is the CTG test safe for the baby?

Yes. The test uses external ultrasound and pressure sensors. No needles, catheters, or internal procedures are involved. The ultrasound component uses the same technology as routine antenatal scans.

How long does a CTG test take?

Typically 20–40 minutes. If the fetus is in a sleep cycle and the trace is not yet reactive, monitoring may be extended until an adequate trace is obtained.

Does the CTG test hurt?

No. The sensor belts may feel firm around the abdomen and remaining still for an extended period can be uncomfortable, but the procedure involves no pain.

What is a normal fetal heart rate on CTG?

A normal baseline fetal heart rate sits between 110 and 160 beats per minute, with a variability of 5–25 bpm around that baseline.

Can a patient decline a CTG test during labour?

Yes. Patients retain the right to decline any monitoring or procedure. The clinical team should explain the reason the test has been recommended and what alternative monitoring approaches are available, enabling an informed decision.

What happens if the CTG trace is abnormal?

The clinical team will extend monitoring, conduct a biophysical profile ultrasound, reposition the patient, or, if compromise is confirmed during labour, consider expedited delivery. An abnormal trace initiates a structured assessment rather than an immediate intervention.

When is a CTG test indicated during pregnancy?

Primarily in the third trimester and during labour. It is not routine at every antenatal visit in low-risk pregnancies but is indicated whenever a risk factor is present, fetal movement has reduced, or labour is in progress with complications.

Planning your antenatal monitoring? Book a cashless CTG appointment through Visit Health and access same-day obstetric specialist support today.