Single Best Answer (SBA) · Intrapartum Maternal and Fetal Monitoring
A CTG shows decelerations that begin with the onset of each contraction and return to baseline as the contraction ends, mirroring the contraction. Which single type is this, and what is its significance?
Show answer and explanation
Answer: A. Early decelerations, which are usually physiological
Early decelerations
| Deceleration | Timing vs contraction | Usual cause |
|---|---|---|
| Early | Mirrors the contraction (nadir with peak) | Head compression; normal/physiological |
| Variable | Variable timing, abrupt drop | Cord compression |
| Late | Nadir after the contraction peak | Uteroplacental insufficiency (pathological) |
Early decelerations
- Mirror the contraction: onset, nadir and recovery coincide with the contraction.
- Caused by fetal head compression (a vagal response), and are usually physiological/normal.
Why this matters
- Recognising early decelerations as benign avoids unnecessary intervention.
- They are distinguished from late decelerations (which lag the contraction and are pathological) by their timing.
Interpreting decelerations correctly requires relating them to the contraction trace.
Practise every Obstetrics & Gynaecology topic
This is a free sample. Sign up for the full bank of flashcards and exam-style questions on a spaced-repetition schedule, with 20 free stars a day.