Non stress test

NST: A reactive(reassuring) NST meets all the following criteria, others are labeled as non reactive

Baseline Fetal HR between 120 to 160
Good beat-to-beat variability (STV)
Accelerations
1. Heart Rate increases by 15-25 bpm over baseline
2. Increase persists for 15-25 seconds
Absence of decelerations (except early decelerations which may occur with contractions, see below)

Types of Decelerations

Early: Represent normal response to head compression during a contraction. The fetal HR falls almost simultaneously as the contraction and returns to baseline when the contraction ends.

Late: Indicate uteroplacental insufficiency and the need for further investigation or delivery. The fetal HR starts to fall after the contraction starts and ends after the contraction is over.

Variable contraction: are variable in shape and relation to the uterine contraction and represent cord compression.