The Biophysical Profile (BPP) is a non-invasive prenatal test used to assess the health and well-being of a developing fetus. This evaluation is primarily utilized in the third trimester of pregnancy, particularly when there are concerns about the environment inside the womb. The BPP checks for signs of fetal compromise, which may be linked to issues with the placenta or other maternal health conditions. It combines two distinct monitoring methods to provide a comprehensive picture of the baby’s current status.
What Exactly is a BPP Ultrasound
The Biophysical Profile integrates real-time ultrasound observation with a Non-Stress Test (NST). The ultrasound portion uses a transducer placed on the abdomen to create images of the fetus using high-frequency sound waves. This safe procedure visualizes the baby’s movements and the surrounding amniotic fluid.
The NST involves placing two belts around the abdomen to track the fetal heart rate and uterine contractions. The NST specifically looks for heart rate accelerations that occur in response to fetal movement, indicating a healthy central nervous system and adequate oxygenation. The entire process usually takes 30 minutes, but may take up to an hour if the baby is resting quietly.
Reasons for Needing a Biophysical Profile
The BPP is often needed when a pregnancy is classified as high-risk, requiring closer monitoring. Common indications include chronic maternal health conditions such as preeclampsia or pre-existing or gestational diabetes. These conditions can potentially affect placental function, which delivers oxygen and nutrients to the fetus.
A BPP may also be ordered if the mother reports a decrease in the frequency or strength of fetal movements, which can signal compromise. Other frequent reasons include suspected intrauterine growth restriction (IUGR) or a pregnancy extending past 41 weeks. The test is also utilized following a previous stillbirth or when there are issues with amniotic fluid volume, such as oligohydramnios or polyhydramnios.
The assessment helps determine if the intrauterine environment remains supportive or if intervention, such as early delivery, might be necessary.
The Five Components of Fetal Assessment
The Biophysical Profile assesses five distinct variables, each scored zero or two points for a normal finding, totaling a possible ten points.
Fetal Breathing Movements
This component is normal if the ultrasound shows at least one episode of rhythmic breathing lasting 30 seconds or longer within the 30-minute observation. These movements involve the baby practicing diaphragm motion by moving amniotic fluid in and out of the lungs.
Gross Body Movement
Two points are scored if the baby exhibits three or more discrete movements of the body or limbs. These movements are an immediate reflection of the baby’s neurological state and muscular function.
Fetal Tone
Fetal Tone is assessed by looking for at least one episode of active extension and immediate return to flexion of a limb or the spine. This indicates good muscle control.
Amniotic Fluid Volume (AFV)
AFV indicates long-term placental health. A normal score requires finding at least one single deepest vertical pocket of amniotic fluid measuring greater than two centimeters in depth. Reduced fluid volume can signal that blood flow is being shunted away from the fetal kidneys, leading to decreased urine output.
Non-Stress Test (NST)
The NST evaluates the fetal heart rate’s reactivity. A normal, or “reactive,” NST is awarded two points if there are two or more heart rate accelerations. Each acceleration must increase the rate by at least 15 beats per minute for 15 seconds, all within a 20-minute window.
Understanding Your BPP Score
The scores from the five components are added together to produce a total BPP score ranging from zero to ten.
A score of eight or ten is considered reassuring, indicating the fetus is healthy and well-oxygenated. This usually means the pregnancy can continue with routine monitoring, suggesting a very low risk of immediate distress.
A score of six is considered equivocal or borderline, suggesting potential compromise. The healthcare provider may recommend a repeat BPP within 12 to 24 hours or order further specialized testing. The approach depends heavily on the baby’s gestational age and the underlying reason for the test.
A score of four or less is considered abnormal and nonreassuring, signaling a higher risk of fetal compromise. Scores in this range prompt serious consideration for immediate intervention, often involving delivery if the baby is at or near term. If the baby is premature, a low score may lead to close observation in the hospital or additional tests.