The biophysical profile is another test used to assess fetal well-being. It involves performing an NST to assess fetal heart rate and ultrasound over 30 minutes to assess fetal breathing movements, gross body movements, tone, and amniotic fluid index (AFI).Two points are given for each variable if present and zero if absent during the observation period (see Table 1–1). A score of 8–10 is considered normal, 6 is equivocal and warrants a repeat BPP in 24 hours, and 0–4 is abnormal with delivery usually indicated. Changes in the BPP parameters are due to fetal hypoxemia. Caution is needed since it can also be affected by other factors such as gestational age, medications, and improper technique. The BPP is widely used among institutions to monitor high-risk pregnancies. However, evidence from randomized clinical trials does not support its use to monitor complicated pregnancies. Institutional variation exists regarding gestational age for performance of BPP, starting as low as 24 weeks, even when its utility has only been studied at higher gestational ages.
Modified biophysical profile. The BPP scoring system has been modified to shorten testing time. The most common combination includes an evaluation of only an NST and AFI. In some cases, the modified BPP is used as an initial test and if abnormal, it is followed by additional testing including a full BPP. The stillbirth rate within 1 week of a normal BPP or a modified BPP is the same at 0.8 per 1000.