At what gestational age can you start doing Biophysical Profile (BPP) prenatally?

From the Guidelines

Biophysical Profile (BPP) testing can be initiated at 28 weeks of gestation for most pregnancies, but it may start as early as 26 weeks in high-risk pregnancies. The decision on when to start BPP testing is crucial for monitoring fetal well-being, especially in cases where there are concerns about placental insufficiency or other conditions that might compromise fetal health 1.

Key Considerations for BPP Testing

• The test evaluates fetal well-being through assessment of parameters such as fetal breathing movements, gross body movements, fetal tone, amniotic fluid volume, and non-stress test (NST) results.
• Fetal behavioral states become more established and predictable after 28 weeks, allowing for more accurate interpretation of BPP results.
• Before 26 weeks, fetal movement patterns and behavioral states are less consistent, which can lead to false interpretations.
• BPP is particularly valuable for monitoring high-risk pregnancies, including those complicated by maternal hypertension, diabetes, decreased fetal movement, intrauterine growth restriction, or post-term pregnancies.

Evidence-Based Recommendations

The most recent and highest quality study 1 supports the initiation of BPP testing at 28 weeks for most pregnancies, with the option to start earlier at 26 weeks for high-risk cases. This approach is based on the understanding that BPP provides a comprehensive assessment of fetal status, helping guide management decisions regarding the timing of delivery.

Clinical Application

In clinical practice, the decision to initiate BPP testing should be based on individual patient risk factors and the gestational age of the fetus. For example, pregnancies at risk for fetal growth restriction (FGR) may require more frequent testing, including weekly or even daily assessments of amniotic fluid volume and other parameters of fetal well-being 1.

Conclusion is not needed, and the answer is based on the provided evidence and guidelines.

The initiation of BPP testing at 28 weeks, or as early as 26 weeks in high-risk pregnancies, is supported by current evidence and guidelines 1, emphasizing the importance of timely and appropriate fetal monitoring to optimize outcomes in terms of morbidity, mortality, and quality of life.

From the Research

Biophysical Profile (BPP) Prenatally

• The Biophysical Profile (BPP) is a prenatal test used to assess fetal wellbeing, typically in high-risk pregnancies.
• The test includes ultrasound monitoring of fetal movements, fetal tone, and fetal breathing, as well as assessment of liquor volume and fetal heart rate 2.
• According to a study published in 2018, weekly ultrasonographic biophysical profiles can be initiated at 32 weeks of gestation in women with preexisting medical conditions 3.
• Another study from 1994 used a modified biophysical profile, which combines a nonstress test and an amniotic fluid index, and found that it can be used biweekly in high-risk pregnancies 4.
• There is no specific gestational age mentioned in the studies as the absolute starting point for BPP, but based on the available evidence, it appears that BPP can be started at around 32 weeks of gestation in high-risk pregnancies 3, 4.

Key Findings

• A study from 2008 found that the use of BPP as a test of fetal wellbeing in high-risk pregnancies is not supported by available evidence 2.
• The 2018 study found that the use of ultrasonographic biophysical profile in a high-risk cohort is associated with a very low test-positive rate and a very low incidence of intrauterine fetal demise 3.
• The 1994 study found that the modified biophysical profile is an excellent means of fetal surveillance and identifies a group of patients at increased risk for adverse perinatal outcome and small-for-gestational-age infants 4.

Gestational Age and BPP

• While there is no specific gestational age mentioned as the starting point for BPP, the available evidence suggests that it can be started at around 32 weeks of gestation in high-risk pregnancies 3, 4.
• A study from 1991 found that biophysical profile scores do not precisely reflect fetal hypoxemia, acidemia, or hypercarbia, and that fetal condition should be evaluated on the basis of fetal blood gas data obtained by cordocentesis, especially in premature or growth-retarded fetuses 5.