What to Expect During BPP and NST Monitoring for FGR?

When you are diagnosed with fetal growth restriction (FGR) due to placental insufficiency, it is normal to feel anxious about your baby’s well-being. To ensure your baby remains safe, your care team will monitor them closely. The two main tools used for this surveillance are the Biophysical Profile (BPP) and the Non-Stress Test (NST).

These tests provide indirect, short-term evidence of your baby’s current well-being ^[1]. They cannot directly measure oxygen or pH levels, but they look for signs that suggest the baby is coping well or signs that could indicate fetal compromise ^[2]. Because placental insufficiency means the placenta may not be delivering nutrients and oxygen efficiently, your doctor will use these tests to watch for changes. The testing schedule is highly individualized—depending on your baby’s gestational age, Doppler results, and your own health, you might have one or both tests weekly, twice a week, or on another schedule entirely ^[1][3].

Urgent Warning: Don’t Wait for Your Next Test

While frequent monitoring is reassuring, it only provides information for the time of the test and cannot predict sudden events like placental abruption ^[4]. If you experience decreased or changed fetal movement, vaginal bleeding, leaking fluid, regular painful contractions, or severe upper abdominal pain, contact your maternity unit or go to obstetric triage immediately. Do not wait for your next scheduled NST or BPP.

The Non-Stress Test (NST)

An NST measures your baby’s heart rate in response to their own movements. It is called “non-stress” because nothing is done to place stress on the baby. The test usually takes 20 to 40 minutes. Belts are placed across your abdomen to monitor the baby’s heart rate and any uterine contractions.

A healthy baby’s heart rate usually increases (accelerates) when they move. Your care team looks for a specific number of adequate accelerations within a set timeframe. If these criteria are met, the test is considered reactive, which is a reassuring sign for that gestational age ^[5].

If the test is non-reactive, it does not automatically mean your baby is in trouble. Babies have sleep cycles, and your team may extend the test, use a buzzer to wake the baby, or move on to a BPP ^[1]. Additionally, very early gestational age or a recent injection of antenatal corticosteroids (given to help mature the baby’s lungs if early delivery is a possibility) can temporarily cause a non-reactive reading, which your doctor will consider when interpreting the results ^[6].

The Biophysical Profile (BPP)

A BPP combines an ultrasound with an NST. The ultrasound looks for four specific signs over a set time period (usually up to 30 minutes). Each component gets 2 points if normal, or 0 points if abnormal or not seen:

• Fetal Breathing: Rhythmic breathing movements of the baby’s chest.
• Fetal Movement: The baby moving their body or limbs.
• Fetal Tone: The baby flexing and extending their arms, legs, or hands.
• Amniotic Fluid Volume: Measuring pockets of fluid to ensure there is an adequate amount, which is a longer-term marker of placental function ^[7][1].

When combined with the NST (2 points if reactive, 0 if non-reactive), the full BPP score is out of 10. Sometimes, the NST is skipped, making it an ultrasound-only score out of 8 ^[7].

What Do the Scores Suggest?

BPP scores are an indirect measure and do not trigger automatic decisions; your doctor will interpret them alongside everything else ^[8].

• 8/8 or 8/10 to 10/10: Usually considered reassuring signs of current well-being ^[7][9]. However, if an 8/10 is due to low amniotic fluid, that requires specific attention because fluid levels reflect longer-term placental function.
• 6/8 or 6/10: Considered an equivocal (borderline) score. This usually prompts closer assessment. It might mean repeating the test later that day, extending the observation time, or considering delivery, depending heavily on your baby’s gestational age and other factors ^[10][8].
• Below 6: An abnormal score that suggests possible fetal compromise ^[8]. This warrants prompt clinician assessment. Depending on the full picture, your team might recommend hospital admission, administering antenatal corticosteroids (if preterm birth is likely), or planning an early delivery ^[1][8].

How Do These Tests Decide Delivery?

Delivery decisions are a complex balancing act. Continuing the pregnancy allows the baby more time to grow but carries risks if the placenta is failing; delivering early avoids placental risks but introduces the challenges of prematurity.

To make this decision, your doctor combines your NST and BPP results with your baby’s growth trend, your own health (like blood pressure), and most importantly, umbilical artery Doppler ultrasounds ^[1][3]. These ultrasounds measure the resistance of blood flow in the umbilical cord. A specific finding called absent or reversed end-diastolic flow (meaning the blood flow momentarily pauses or flows backward between heartbeats) is a major sign of placental strain and heavily influences the decision to deliver early ^[11][1].

No single score makes the decision. Your care team will look at the entire puzzle to choose the safest possible time for your baby to be born.