WEIGHTED BIOPHYSICAL PROFILE SCORE

Score	Biophysical parameter	Normal	Abnormal
4	Amniotic fluid	Normal AFI	AFI less than 5cm
3	Non stress test	At least two episodes of FHR acceleration of greater than or equal to 15 bpm of at least 15 sec duration	Less than two episodes of FHR acceleration of <15 bpm in 30 min
2	Fetal breathing	At least one episode of fetal breathing of at least 30 sec duration in 30 min of observation	Absent fetal breathing or no episode of greater than or equal to 30 sec in 30 mins
1	Gross body movements	At least three discrete body or limb movements in 30 min (episodes of continuous movement is considered a single movement)	Two or fewer episodes of body or limb movements in 30 mins
0	Fetal tone	At least one episode of active extension with return to flexion of fetal limb(s) or trunk; opening and closing of a hand is normal tone	Absent or slow extension with return to partial flexion

AFI = Amniotic fluid index.
bpm = Beats per minute.
min = Minutes.
sec = Seconds.

Maximum Score = 10
Minimum Score = 0

Each component of the biophysical profile is controlled by a different structure within the fetal brain:

• Fetal tone - Cerebral cortex.
• Fetal movements - Cerebral cortex and motor nuclei.
• Fetal breathing - Centers close to the fourth ventricle.
• Non stress test - Posterior hypothalamus and medulla.
• Amniotic fluid - Fetal urine production (placental function and perfusion of the fetal kidneys).

According to the gradual hypoxia concept, biophysical activities that were first evident in the fetus are the last to disappear in fetal hypoxia. Therefore the different components of the biophysical profile score have different sensitivity levels to hypoxia and therefore should not be scored equally. The fetal heart rate center is the most sensitive to hypoxia while the fetal tone-regulating center in the cortex is the least sensitive. The weighted biophysical profile score considers the relative importance of individual parameters. Fetal tone had the lowest predictive value and was not ranked. Amniotic fluid is given the highest value and represents chronic hypoxia. These fetuses are more prone to cord accidents.

REFERENCES

1. Petrikovsky BM, Baker DA. A new proposal for a fetal biophysical profile scoring system. Am J Gynecol Health 1991;16:2-35.
2. Petrikovsky BM, Smith-Levitan M, Gross B. Weighted biophysical profile score - ready for clinical use. Isr J Obstet Gynecol 1998;9:77-79.
3. Petrikovsky BM. Editorial. Fetal assessment: time to reassess. Ultrasound Obstet Gynecol 1999;13:297-298.