Normal Fetal Movements
Normal fetal movement: perceived fetal movements are defined as the maternal sensation of any discrete kick, flutter, swish or roll.
Characteristics of normal fetal movement:
| Characteristics | Description |
|---|---|
| Onset and progression | Most women become aware of fetal activity between 18 and 20 weeks of gestation
The number of movements typically increases until the 32 weeks, after which the frequency plateaus until labour (but there should NOT be a reduction in the frequency of fetal movement) |
| Frequency | Average: 31 generalised movements per hour
Normal range: 16-45 movements per hour |
| Patterns and cycles | A normal fetus goes through regular periods of rest and sleep throughout the day and night
|
Abnormal Fetal Movements (AFM)
Note that there is no universally agreed-upon definition of RFM due to a lack of robust epidemiological studies on normal fetal activity patterns.
RCOG highlighted several clinical markers of AFM:
- A significant reduction or sudden alteration in fetal movement
- Any subjective maternal concern about a reduction or cessation of movements after 28 weeks of gestation is treated as a potential indicator of abnormal movement that requires clinical assessment
Women should be reassured that 70% of pregnancies with a single episode of RFM are uncomplicated.
Clinical Implications
Maternal perception of fetal movement is a key indicator of fetal well-being. The main implications include:
- Impending fetal death
- Stillbirth
- Fetal compromise (e.g. IUGR, SGA, placental insufficiency)
- Underlying fetal abnormalities (e.g. major fetal malformation, CNS abnormalities, musculoskeletal abnormalities, underlying neuromuscular conditions)
Risk factors for RFM (those associated with stillbirth and IUGR):
- Hypertension and diabetes
- Extremes of maternal age
- Primiparity
- Maternal obesity and smoking
- Congenital malformations and genetic factors
Certain factors may influence fetal activity or maternal perception (transient / non-pathological causes of RFM):
- Maternal posture (women perceive the fewest movement while standing, and the most when lying down)
- Maternal distraction
- Fetal position (fetal spine lying anteriorly)
- Sedating drugs (e.g. alcohol, benzodiazepines, methadone, opioids)
- Antenatal corticosteroids
When to Seek Help (Patient Counselling)
If a woman is concerned about a reduction or cessation of fetal movements after 28 weeks of gestation → contact the maternity unit immediately
If the woman is unsure whether movements are reduced:
- Lie in the left lateral position and focus on fetal movements for 2 hours
- If <10 discrete movements felt over 2 hours → contact maternity unit immediately
Investigation and Work-Up
If fetal movements are never felt in those who are <24 weeks of gestation → refer to a specialist fetal medicine centre.
RFM in <28 Weeks of Gestation
Immediate step: check fetal viability with a handheld Doppler device
- To auscultate for the presence of a fetal heartbeat
- If there is no fetal heartbeat → immediate ultrasound scan assessment to exclude or diagnose intrauterine fetal death
In settings where auscultation cannot be performed, refer the woman to the maternity unit for evaluation.
CTG is NOT routinely performed before 28 weeks of gestation, due to an immature fetal autonomic nervous system. [Ref]
If performed at this gestation, findings must be interpreted with caution, as features considered abnormal at term may represent normal preterm physiology. [Ref]
RFM in >28 Weeks Gestation
Immediate step: check fetal viability with a handheld Doppler device (fetal heartbeat auscultation)
- Fetal heartbeat present (i.e. fetal viable) → CTG assess for fetal compromise
- Normal CTG: accelerations coinciding with movements
- If concerns remain despite a normal CTG → ultrasound scan assessment
- Fetal heartbeat absent → immediate ultrasound scan assessment to exclude or diagnose intrauterine fetal death
In settings where auscultation cannot be performed, refer the woman to the maternity unit for evaluation.