What is a Fetal Fibronectin Test?
Pregnancy is a complex process in all aspects. At each stage, the expectant mother goes through a series of biological changes. The production of fetal fibronectin, a protein that acts as a biological adhesive and helps keep the amniotic sac attached to the uterine lining, is also involved in this complex process. In this article, we have tried to give as much information as possible about fetal fibronectin .
What is Fetal Fibronectin (fFN)?
Fetal Fibronectin (or fFN) is a protein produced by the nerve cells of the amniotic sac during pregnancy. It acts as a biological glue that binds the amniotic sac to the uterine lining. The amniotic sac is the fluid-filled sac that surrounds the baby. fFN occurs naturally in cervicovaginal secretions until the first 22 weeks of pregnancy and then at the end of the third trimester. If it is detected between the 22nd and 34th weeks, it indicates the possibility of premature birth.
Fetal fibronectin testing is performed to prevent premature birth. We’ll also provide some information about who should take the test or who is more likely to get it.
What is a Fetal Fibronectin Test?
If the baby is born between the 20th and 37th weeks of pregnancy, this is called a preterm birth. Preterm births pose health risks to the baby because they do not complete fetal development, and the risk of infant death is higher. A fetal fibronectin test is used to check for signs of preterm labor.
The test helps the gynecologist measure the connection between the amniotic sac and the uterus. If the infection is disrupted by inflammation, shortening of the cervix, or uterine contractions, fFN is released into cervical secretions. In the fetal fibronectin test, a cervical secretion swab is collected and tested to test for preterm birth. If fFN is found, the mother is at risk of premature birth.
Who Should Have a Fetal Fibronectin Test?
An fFN test is used to check for signs of preterm labor so that precautionary measures can be taken for the health and safety of the fetus. The fFN test is recommended by an obstetrician for pregnant women in the following cases.
- Those who are at high risk of preterm birth due to a short cervix, a history of preterm birth or the fact that the pregnancy occurred shortly after the previous one, or lifestyle factors such as substance abuse,
- It is recommended for women who show symptoms such as persistent back pain, pelvic or lower abdominal pressure or tightness, vaginal bleeding or spotting, abdominal cramping, increased vaginal discharge, or watery vaginal discharge.
When is this test done?
An obstetrician will recommend that an fFN test be performed if they suspect preterm labor.
- The fFN test can be performed between the 22nd and 35th week of pregnancy, as it is the period when fFN should ideally be absent in cervicovaginal secretions. The test is performed on pregnant women who show signs and symptoms of preterm labor, such as uterine contractions, change in vaginal discharge, abdominal cramps and discomfort, pelvic pressure, or back pain.
- If signs of labor persist for several weeks after a negative test, the test may be repeated. Since each test result is only valid for 7 to 14 days, the test can be repeated several times as needed.
- It can also be done if the pregnant woman is at high risk of preterm birth due to lifestyle factors such as a short cervix, a history of preterm labor, a short interval between two pregnancies, or substance abuse.
The fFN test can often give a false positive result, and as such, certain precautionary measures must be taken to increase the chances of an accurate result. To prepare for the test:
- Avoid sexual intercourse for 24 hours before the test, as the sperm contains enough fFN to alter the result and give a false positive.
- It is necessary not to have a pelvic exam or transvaginal ultrasound before the fFN test, as it can cause the release of the fFN protein, making the fetal fibronectin test positive.
- Avoid douching, using soaps, lotions, lubricants, or medications near your vagina for at least 24 hours before the test.
- In case of vaginal bleeding, inform the health institution as it may lead to a false result.
The fFN test is a helpful tool in predicting preterm labor so that precautionary steps can be taken. It is done by taking a swab from the cervicovaginal secretion. Read below to learn a little more about what you can expect during and after the test.
What are the Fetal Fibronectin Test Results?
The results of an fFN test can be positive or negative.
1. Positive
Positive laboratory test results mean that the discharge contains the fFN protein. A positive result between the 22nd and 35th weeks of pregnancy is an indication of an increased risk of preterm birth with neonatal complications in the next seven days. However, since a positive result is not completely reliable, an additional pelvic exam or vaginal ultrasound may be performed.
If the result is positive, steps should be taken to ensure the safe delivery of the baby and increase the chances of survival. This may include taking steroids to make the fetus’s lungs mature faster, or medications to reduce the risk of neurological complications in the baby, such as cerebral palsy. If the mother has vaginal contractions, she may also be given medications to temporarily stop them.
2. Negative
A negative fetal fibronectin test is indicative of the absence of the fFN protein in the vaginal secretion, so the mother’s chances of giving birth in the next two weeks are minimal (1%). However, if the symptoms persist for a few more weeks, another test may be done.
