CTG in Pregnancy: What It Shows, Timing and Results
Reviewed by the LabReadAI medical team
CTG (cardiotocography) is a simple, safe way to assess how the baby is doing: the device records its heartbeat and uterine tone. The report leaves the mother with "baseline rate", "variability", "Fisher score". Let's break down what CTG shows in pregnancy, its timing, and how to read the results — so the timing and the results on the report make sense.
What Fetal CTG (Cardiotocography) Shows
CTG simultaneously records the fetal heart rate, its changes in response to movements and uterine tone (contractions). This shows whether the baby gets enough oxygen and how it responds to load. It is a functional assessment of the fetus — it complements ultrasound in pregnancy, which looks at structure.
When CTG Is Done
CTG is informative from the third trimester (usually from 30–32 weeks), when the nervous regulation of the fetal heart matures. In labour, CTG monitors the baby. A recording lasts about 20–40 minutes; sometimes longer if the baby is "asleep".
Reading the Values: Baseline and Fisher Score
| Value | Norm / meaning |
|---|---|
| Baseline FHR | 110–160 bpm |
| Variability | 5–25 bpm (a good sign) |
| Accelerations | rises with movements — good |
| Decelerations | drops — the type and link to contractions matter |
| Fisher score | 8–10 normal, 6–7 doubtful, ≤5 alarming |
| FSI | up to 1.0 normal; higher warrants follow-up |
Low variability, late decelerations and low scores warrant attention and a repeat/clarifying assessment.
Is Preparation Needed
No special preparation; it is better to come not fasting and calm, and use the toilet before the recording. If the fetus is inactive, the doctor may extend or repeat the test.
When to See a Doctor
Tell your doctor about low scores, an abnormal rate, marked decelerations, and if you notice a sharp decrease in your baby's movements. CTG is assessed together with ultrasound and the overall plan — what tests are done in pregnancy.
To understand your CTG report in plain language, upload it (PDF or photo) to the imaging interpretation service: the AI will explain the values for the dates. This helps you understand the result but does not replace an obstetrician.
This article is informational. CTG interpretation and management are the doctor's job.
For informational purposes only
This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Please consult a healthcare professional for medical guidance.