Fetal Movement and Health Indicators

Fetal Movement

• Fetal movement is a key indicator of fetal health
• A change in the normal number of fetal movements may indicate the fetus is under stress
• The simplest way to chart movements is to record the amount of time it takes to feel 10 movements. It should take no more than 2 hours.
• Most fetuses have circadian rhythms and are more active in the evening hours.
• A fetus will often be more active an hour after the mother eats.
• The mother will likely begin feeling fetal movements (quickening) around 16-25 weeks of pregnancy. The average is 20-22 weeks, but can be earlier for those who have had multiple pregnancies.

Fetal Movement Count

• A fetus spends 10% of its time making gross fetal body movements
• It makes approximately 30 movements each hour
• Active periods for fetal body movement typically last about 40 minutes
• Quiet periods generally last about 20 minutes
• The longest period without fetal movement should not be more than 75 minutes

Factors Affecting Perception of Fetal Movement

• Fetal and Placental factors:
  • Placental location
  • Length and type of fetal movements
  • Amniotic fluid volume (AFV)
• Maternal factors:
  • Parity
  • Obesity

Ultrasound for Fetal Parameters

• Basic Ultrasound - Done at 10-14 weeks.
  • Number of fetuses
  • Fetal heart and viability
  • Gestational age - CRL
  • Any gross anomaly - anencephaly, limb reduction defects
  • Nuchal translucency
  • Placental localization
  • Cervical length
  • Maternal pelvic masses

2nd & 3rd Trimester Ultrasound

• Serial Measurements - Done at 10-14 weeks.
  • BPD, AC, HC, FL (Growth US Scan)
  • HC/AC Ratio: Exceeds 1 before 32 weeks. After 34 weeks, it falls below 1. In symmetric IUGR, it remains normal. This ratio can identify 85% of IUGR fetuses.

Internal Cardiotocograph

• Uses an electronic transducer connected directly to the fetal scalp through the cervical opening.
• Connected to a monitor
• Requires ruptured amniotic membranes
• Requires a dilated cervix (2 cm)
• Cephalic presentation with the presenting part down against the cervix

Non-Stress Test (NST) Method

• Patient positioned in a lateral tilt position
• FHR and uterine activity monitored with an external transducer
• FHR monitored for 20 minutes
• Monitoring extended for 40 minutes in cases to compensate for sleep cycles - Extended NST
• Acoustic stimulation used if the fetus is not reactive.

Intrapartum CTG Interpretation

• Baseline Fetal Heart Rate (FHR)
• Baseline FHR Variability
• Presence of Accelerations
• Decelerations
• Uterine Activity (contractions)

Fetal Heart Baseline

• Differentiate between fetal and maternal heartbeats.
• Baseline FHR usually ranges between 110 and 160 beats/minute.
• Fetal Tachycardia - Baseline FHR greater than 160 beats per minute
• Fetal Bradycardia - Sustained fetal heart rate less than 110 beats per minute

Causes of Fetal Tachycardia

• Maternal fever
• Chorioamnionitis
• Fetal sepsis
• Drugs (Atropine, Phenothiazines, Beta-sympathomimetics)
• Tachyarrhythmias
• Fetal heart failure
• Severe fetal anemia, fetal hydrops
• Maternal hyperthyroidism

Variability

• Variability normally ranges between 5 and 25 beats/minute.
• Intermittent periods of reduced baseline variability are normal, especially during sleep.

Causes of Decreased Variability

• Hypoxemia/acidosis
• Fetal sleep cycles
• Drugs (Analgesics, barbiturates, phenothiazines, anesthetics)
• Prematurity
• Arrhythmias
• Pre-existing neurological abnormality
• Congenital anomalies

Accelerations

• Increase in FHR greater than or equal to 15 bpm for greater than or equal to 15 seconds from the onset to return to baseline.
• The presence of accelerations, even with reduced baseline variability, is generally a sign that the baby is healthy.
• The absence of accelerations on an otherwise normal cardiotocograph does not indicate fetal acidosis.
• Digital fetal scalp stimulation (during vaginal examination) that leads to an acceleration in fetal heart rate is a sign that the baby is healthy.

Decelerations

• Decreases in fetal heart rate from the baseline by at least 15 bpm, lasting for at least 15 seconds.

Types of Decelerations

• Early Decelerations:

  • Begin at the start of uterine contraction and end with conclusion of contraction.
  • The onset, nadir, and recovery of the deceleration are with the beginning, peak, and ending of the contraction, respectively (mirror like).
  • Related to head compression.
  • Early decelerations are a benign finding caused by a vasovagal response as a result of fetal head compression by the contraction.
  • No intervention necessary. Just continue to watch for any changes.

• Variable Decelerations:

  • Variable in duration, intensity, and timing.
  • Abrupt(sudden) decrease in FHR of > 15 beats per minute measured from the most recently determined baseline rate.
  • The onset of deceleration to nadir is less than 30 seconds. The deceleration lasts > 15 seconds and less than 2 minutes.
  • Related to cord compression.

• Late Decelerations:

  • Gradual decrease in FHR with onset of deceleration to nadir > 30 seconds.
  • Onset of the deceleration occurs after the beginning of the contraction, and the nadir of the deceleration occurs after the peak of the contraction.
  • Related to decreased uteroplacental perfusion.

EFM Learning Points

• It is used to identify intrapartum hypoxia, a significant cause of fetal death and disability. Fetal hypoxia can lead to fetal asphyxia and death.
• It should not be used unless indicated as it increases the rates of cesarean section and instrumental delivery in low-risk women.
• It has become an integral component of labor management in high-risk women.

Intermittent Auscultation of Fetal Heart Rate

• Intermittent auscultation of the fetal heart rate can be used for women at a low risk of complications in the established first stage of labor.
• Auscultate immediately after a contraction for at least 1 minute, at least every 15 minutes in the first stage of labor, and at least every 5 minutes in the second stage. Record as a single rate.