From the Guidelines
A biophysical profile (BPP) is typically performed after 28 weeks of gestation, though it may be initiated as early as 26 weeks in high-risk pregnancies. The optimal timing is in the third trimester when fetal physiological systems are sufficiently developed to demonstrate the parameters being assessed. BPPs are most commonly ordered weekly or twice weekly for pregnancies with risk factors such as decreased fetal movement, intrauterine growth restriction, preeclampsia, diabetes, or post-term pregnancy. The test evaluates fetal well-being through five components: fetal breathing movements, gross body movements, fetal tone, amniotic fluid volume, and non-stress test results. Before 26 weeks, some of these parameters may not be reliably assessed as fetal neurological development is still progressing. The timing of BPP initiation should be individualized based on the specific risk factors present, with more frequent testing recommended as the pregnancy approaches term or if concerning findings are noted on initial assessment 1.
Some key points to consider when determining the gestational age for a BPP include:
- The presence of risk factors, such as decreased fetal movement or intrauterine growth restriction, which may necessitate earlier initiation of BPP 1.
- The fetal physiological systems must be sufficiently developed to demonstrate the parameters being assessed, which is typically after 28 weeks of gestation 1.
- The frequency of BPP testing should be individualized based on the specific risk factors present and the pregnancy's progression 1.
- The BPP is an important tool for assessing fetal well-being, but it should be used in conjunction with other tests, such as non-stress testing and Doppler velocimetry, to provide a comprehensive picture of fetal health 1.
In summary, while there is no one-size-fits-all answer to the question of when to perform a BPP, the general consensus is to initiate BPP after 28 weeks of gestation, with earlier initiation in high-risk pregnancies. The specific timing and frequency of BPP testing should be determined on a case-by-case basis, taking into account the individual pregnancy's risk factors and progression 1.
From the Research
Gestational Age for Biophysical Profile (BPP)
The appropriate gestational age for a Biophysical Profile (BPP) can vary depending on the specific circumstances of the pregnancy.
- According to 2, the median gestational age at entry for BPP testing was 25 weeks and 1 day, and at delivery was 29 weeks and 6 days.
- 3 suggests that BPP scoring can be used from the second trimester onward, as it correlates with current fetal pH.
- 4 recommends that antepartum fetal surveillance, including BPP, should begin at the gestational age at which delivery would be considered.
- 5 found that BPP scoring, along with Doppler ultrasound and computerized fetal heart rate analysis, can be used to predict acid-base status in growth-restricted fetuses, with a median gestational age of 30 + 6 weeks at delivery.
- 6 suggests that fetal surveillance, including BPP and Doppler examination, should be initiated after 32 weeks of gestation in growth-restricted fetuses, but notes that evaluation of fetal state before 32 weeks is difficult and may require additional tests.
Key Findings
- BPP scoring can be used from the second trimester onward to assess fetal well-being.
- The gestational age at which BPP testing is initiated may depend on the specific circumstances of the pregnancy, such as the presence of growth restriction or other high-risk conditions.
- BPP scoring, along with other tests such as Doppler ultrasound and computerized fetal heart rate analysis, can be used to predict acid-base status and guide management decisions.