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  • Early decelerations are due to head compression (stimulation of vagus nerve)
  • Late decelerations are due to uteroplacental insufficiency (fetal distress/hypoxia)
  • Variable decelerations are due to cord compression (oligohydramnios in labor)

Features of Early Fetal Heart Rate Deceleration


Characteristics include gradual decrease in the h "art rate with both onset and recovery coincident with the onset and recovery of the contraction.



Features of Late Fetal Heart Rate Deceleration


Characteristics include gradual decrease in the heart rate with the nadir and recovery occurring after the end of the contraction, The nadir of the deceleration occurs 30 seconds or more after the onset-of-the deceleration.




Late deceleration is consequence of uteroplacental-induced hypoxia.

Features of Variable Fetal Heart Rate Decelerations


Characteristics include abrupt decrease in the heart rate with onset commonly varying with successive contractions.


The decelerations measure ≥ 15 beats/min for 15 seconds or longer with an onset-to-nadir phase of less than 30 seconds. Total duration is less than 2 minutes.


Prolonged Deceleration


Defined as an isolated deceleration lasting 2 minutes or longer but less than 10 minutes from onset to return to baseline. Causes of prolonged deceleration:

  1. Uterine hyperactivity
  2. Maternal supine hypotension, maternal hypoperfusion or hypoxia from any cause
  3. Placental abruption
  4. Umbilical cord knots, cord entanglement or cord prolapse
  5. Maternal seizures including eclampsia and epilepsy
  6. Cervical examination and application of a fetal scalp electrode.

Wandering Baseline

This baseline rate is unsteady and "wanders" between 120 and 160 beats/min. This rare finding is suggestive of a neurologically abnormal fetus and may occur as a preterminal event.

Cardiac Arrhythmia

When fetal cardiac arrhythmias are first suspected using electronic monitoring, findings can include baseline bradycardia, tachycardia, or most commonly, abrupt baseline spiking.

Fetal Scalp pH

According to the ACOG, measurements of the pH in capillary scalp blood may help to identify the fetus in serious distress.

  1. The pH of fetal capillary scalp blood is usually lower than that of umbilical venous blood and approaches that of umbilical arterial blood.
  2. If the pH is greater than 7.25, labor is observed. If the pH is between 7.20 and 7.25, the pH measurement is repeated within 30 minutes. If the pH is less than 7.20, another scalp blood sample is collected immediately and the mother is taken to an operating room and prepared for cesarean section. Delivery is performed promptly if the low pH is confirmed.

Fetal Pulse Oximetry

Using technology similar to that of adult pulse oximetry, instrumentation has been developed that may allow assessment of fetal oxyhemoglobin saturation once the membranes are ruptured. A unique pad-like sensor is inserted through the cervix and positioned against the fetal face, where it is held in place by the uterine wall.


The lower limit for normal fetal oxygen saturation is generally considered to be 30% by most investigators.

Biophysical Profile

Components and Their Scores for, the Biophysical Profile (Manning's score)



Score 2

Score 0

Nonstress test

≥ 2 accelerations of ≥ 15 beats/min for ≥ 15 seconds in

20-40 min i.e. reactive NST

0 or 1 acceleration in 20-40 min

Fetal breathing

≥ 1 episode of rhythmic breathing lasting> 30 seconds

within 30 min

< 30 see of breathing in 30 min

Fetal movement

≥ 3 discrete body or limb movements within 30 minutes

< 3 discrete movements

Fetal tone

≥ 1 episode of extension of a fetal extremity with return to flexon or opening or closing of hand within 30 min

No movements or no extension/ flexion

Amniotic fluid


Single vertical pocket> 2 cm

Largest single vertical pocket s



Biophysical Profile Score, Interpretation, and Pregnancy Management


Biophysical Profile Score


Recommended Management


Normal, nonasphyxiated

No fetal indication for intervention; repeat test weekly except in diabetic patient and postterm pregnancy (twice weekly)

8 Normal fluid

Normal, nonasphyxiated


No fetal indication for intervention; repeat testing per protocol

8 Oligohydramnios

Chronic fetal asphyxia


Deliver if ~ 37 weeks, otherwise repeat testing


Possible fetal asphyxia

If amnionic fluid volume abnormal, deliver


If normal fluid at> 36 wk with favorable cervix, deliver


If repeat test s 6, deliver


If repeat test> 6, observe and repeat per protocol


Probable fetal asphyxia

Repeat testing same day; if biophysical profile score s 6, deliver


Almost certain fetal asphyxia


Color Doppler


  1. IUGR (most important investigation for management)
  2. Rh isoimmunization
  3. Prediction of PIH
  4. Diagnosis of placenta accreta/percreta, vasa previa

Color Doppler

  1. Uterine
  2. Umbilical
  3. Middle Cerebral (MCA)
  1. Ductus venosus
  2. Umbilical


Uterine Artery

Increased impedance of maternal uterine artery velocimetry (presence of diastolic notch) at 16-20 weeks is predictive.

Umbilical artery

  1. Umbilical artery Doppler is considered abnormal if the S/D ratio is above the 95th percentile for gestational age (rising S/D ratio is the earliest change in IUGR).
  2. Absence of diastolic flow in umbilical artery is an ominous sign and IUFD can be expected within 7 days.
  3. In extreme cases of growth restriction, end diastolic flow may become reversed and IUFD will occur within 48 hours.

Middle Cerebral Artery (MCA)

  1. In fetus with IUGR, as the SID ratio begins to rise the blood flow in MCA increases. There is redistribution of blood flow and vital organs like brain continue to receive adequate blood at the expense of liver and kidney. This is called as brain-sparing effect.
  2. Peak systolic velocity (PSV) in the middle cerebral artery is increased with fetal anemia because of increased cardiac output and decreased blood viscosity. PSV in MCA is now used in management of Rh isoimmunized fetuses.

Ductus Venosus

Reversal of flow in umbilical artery will also cause reversal of flow in ductus venosus and thus indicate the severity of IUGR. Pulsations in the umbilical vein is a preterminal event indicating impending IUFD.

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