A fetus displays a baseline heart rate of 125 beats per minute with moderate variability.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

NICHD definitions:

A variable deceleration is identified by:

Abrupt onset(drop from baseline to nadir in <30 seconds)

Depth ≥15 bpm

Duration ≥15 seconds and <2 minutes

Variable timing relative to contractions

Variable shape (sharp drop, jagged descents, rapid recovery)

The scenario describes:

Abrupt drop from 125 → 80 bpm (rapid onset)

Lasting 90 seconds (still <2 minutes)

Gradual return but still within variable range

Occurring during a contraction

Depth >15 bpm

This meets ALL criteria for a variable deceleration.

Why the other options are wrong:

A. Early deceleration

Requires gradual onset (>30 seconds).

Mirrors contraction shape.

Caused by head compression.

This decel is abrupt, so NOT early.

B. Prolonged deceleration

Requires ≥2 minutes and <10 minutes.

This decel lasts 90 seconds, which is below the threshold.

Correct classification: Variable deceleration.