What is considered a deceleration in fetal heart rate?
FHR baseline usually ranges from 120-160 beats per minute (bpm); however, with fetal decelerations, the heart rate usually drops about 40bpm below baseline. Fetal decelerations are classified into three categories (e.g., early, late, and variable) according to their shape and timing relative to uterine contractions.
What do early decelerations indicate?
Early decelerations are caused by compression of the fetal head during uterine contractions. This results in vagal response (a response that occurs when the vagus nerve is stimulated). The vagal response causes a drop in the fetal heart rate.
What do early Decels mean?
Early deceleration is defined as a symmetrical decrease and return of fetal heart rate (FHR) that is associated with a uterine contraction.
What is considered a late deceleration?
Definition. Late deceleration is defined as a visually apparent, gradual decrease in the fetal heart rate typically following the uterine contraction. The gradual decrease is defined as, from onset to nadir taking 30 seconds or more.
What causes fetal heart decelerations?
They are caused by decreased blood flow to the placenta and can signify an impending fetal acidemia. Typically, late decelerations are shallow, with slow onset and gradual return to normal baseline. The usual cause of the late deceleration is uteroplacental insufficiency.
What is a late deceleration?
Late deceleration. A gradual* decrease and return to baseline of the FHR associated with a uterine contraction. The deceleration is delayed in timing, with the nadir of the deceleration occurring after the peak of the contraction.
How do you treat variable decelerations?
Also, you can take certain steps to treat late decelerations and improve fetal oxygen supply.
- Lie down in the left lateral, knee-chest, or right lateral position to relieve compression of the large vein (or vena cava) by your pregnant uterus.
- Your doctor might administer oxygen in response to late decelerations.
What is early deceleration?
Early deceleration. A gradual* decrease and return to baseline of the FHR associated with a uterine contraction. The nadir of the FHR and the peak of the contraction occur at the same time. The deceleration’s onset, nadir, and termination are usually coincident with the onset, peak, and termination of the contraction.
What are early and late decelerations?
Late Decelerations A deceleration is a decrease in the fetal heart rate below the fetal baseline heart rate. An early deceleration is defined as a waveform with a gradual decrease and return to baseline with time from onset of the deceleration to the lowest point of the deceleration >30 seconds.