Fetal Fibronectin Test: A Key To Predicting Preterm Labour
The fetal fibronectin test predicts preterm labour risk by detecting a key protein in pregnancy. Learn about its procedure, timing, significance, and management, ensuring informed decisions for maternal and neonatal health.
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Last updated on 3rd Jul, 2025
The fetal fibronectin is a protein secreted by the mother during pregnancy, which acts as a biological glue in helping attach the amniotic sac to the uterine lining. It is found in cervical and vaginal secretions and becomes detectable during early and late pregnancies. In some cases, its presence might indicate preterm labour.
The fFN (fetal fibronectin) test allows for early medical intervention, which can help enhance pregnancy outcomes. This blog discusses how the test works, its significance, and how it helps healthcare providers manage the risks of preterm labour effectively.
Purpose of the Fetal Fibronectin Test
Preterm birth has been associated with substantial risks for neonatal health, such as respiratory distress syndrome, infections, and developmental delays. It is defined as the delivery of infants before 37 weeks of gestation.
The fFN test helps assess the risk of preterm labour in women presenting with symptoms such as contractions or changes in the cervix.
A positive result indicates the possibility of early delivery, so closer observation and treatment are planned to prevent complications.
The test is frequently advised for women with a previous history of preterm delivery or multiple pregnancies.
In conjunction with other clinical evaluations, the fFN tests help personalise care for each pregnancy.
Women who test positive might be given corticosteroids to aid fetal lung maturation or be advised to bed rest to minimise the risk of preterm labour.
In contrast, a negative result provides peace of mind that preterm labour is unlikely, avoiding unnecessary interventions.
This strategy is vital in streamlining healthcare resources and, at the same time, alleviating the stress and anxiety levels of pregnant women.
How the Fetal Fibronectin Test is Conducted
There is minimal preparation required before the fFN test and one does not have to go through any significant measures.
Patients should refrain from vaginal intercourse, douching, and using vaginal medications for 24 hours before the test. These activities might affect results and cause inaccuracies.
Healthcare providers may also inquire about symptoms or risk factors to determine if a test is appropriate.
Addressing a patient's fears about the process is easier when they are already informed about the procedure.
Step-by-step Test Procedure
Here is a simple and painless procedure for the test:
Step 1: The patient reclines comfortably on an examination table.
Step 2: A healthcare provider uses a sterile speculum to gently insert it into the vagina and shines a light to examine the cervix.
Step 3: A swab is used to collect a sample of vaginal secretions from the cervix.
Step 4: The sample is placed in a sterile container and sent to the laboratory for analysis.
Test results are usually ready in as little as 24 hours to allow for immediate pregnancy intervention decisions. The process is done in just a few minutes, with only slight physical discomfort and no permanent side effects.
Understanding Fetal Fibronectin Test Results
A positive fFN test is when fetal fibronectin is found in vaginal secretions. This is an indication of a slightly greater risk of preterm labour but does not prove it.
A positive result suggests that labour could occur within the next fortnight, but other factors, including cervical length and uterine activity, also need to be taken into account.
Conversely, a negative test result indicates that fetal fibronectin is absent or below detectable levels, indicating that preterm labour is unlikely to occur within the next two weeks.
Significance of Test Timing
The fFN test is most effective between 22 and 34 weeks of gestation, providing the most accurate estimate of preterm labour risk within this timeframe.
Outside of this window, the results may be less reliable, as fFN levels naturally fluctuate in early and late pregnancy.
For women with persistent symptoms or ongoing concerns, the test may be repeated if necessary.
Frequent retesting is not standard practice unless clinically indicated, as repeating the test after a negative result does not provide additional valuable insights.
Risks and Limitations
The fFN test is informative but is not perfect. Contamination, such as the presence of blood, semen or amniotic fluid in the sample, can result in false-positive results. On the other hand, false negatives can result in opportunities for intervention being missed.
These limitations highlight the need to interpret results in the broader clinical context in conjunction with other diagnostic methods, such as cervical length measurement or monitoring of uterine activity.
The test itself is safe and non-invasive; it poses no direct permanent risk to the mother or the baby. However, it can cause some temporary discomfort when taking a sample.
Using the proper technique and sterile conditions can eliminate any risk of complications. The risk associated with this procedure is usually low and is greatly outweighed by the benefits of early detection.
Clinical Implications and Follow-up
Positive fFN results trigger intervention for preterm labour. Common interventions include:
Corticosteroid Therapy: This is performed to accelerate fetal lung maturity, therefore decreasing the incidence of respiratory distress syndrome in premature infants.
Tocolytics: These are drugs that inhibit uterine contractions, extending the duration of pregnancy.
Referral to Specialist: It might be required when the case is complex and requires additional expertise.
Ultrasound: Supportive care has traditionally included ultrasounds on a routine basis to measure cervical length and frequent monitoring for uterine activity.
Taken together, these tools give a holistic picture of preterm labour risk that informs subsequent medical decision-making. Amniotic fluid analysis or biophysical profile may be recommended in some cases to ensure optimal maternal and fetal health.
Alternatives to the Fetal Fibronectin Test
A few approaches used in addition to or instead of the fFN test are:
Ultrasound Measurement of Cervical Length: A short cervix is an established risk factor for preterm birth and is routinely measured in high-risk pregnancies.
Ultrasound-based Biophysical Profiles: These assess the well-being of the fetus using ultrasound as well as fetal heart rate monitoring.
A recent study evaluated hormonal and inflammatory markers, and ongoing research is focused on identifying additional biomarkers that can more accurately predict preterm labour.
Conclusion
The fetal fibronectin test is a highly valuable tool for predicting and managing the risk of preterm labour. It enables timely interventions in at-risk women, which help improve maternal and neonatal outcomes. In spite of its shortcomings, it is still a mainstay of modern obstetric care.
Novel technologies hold the potential for even more accurate prediction of preterm labour. Biomarker and imaging advances can help to make pregnancy even more tailored in the future.
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