Just the word stress in the word nonstress test may cause you a bit of anxiety. Even though it says non, the fact that stress is in there along with test doesn’t really do much to comfort you. Today, I’ll be explaining what a nonstress test (NST) is, how it is performed, what the results might show, and what the risks and benefits might be.
Nonstress Test (NST)
What is a nonstress test (NST)?
It is called a nonstress test because nothing is done to put the baby or yourself in any additional stress. In radiology, there is an exam called a stress test in which the patient is either given medication or asked to walk on a treadmill to put some stress on the cardiovascular system. This is done to evaluate the health of the cardiovascular system while relaxing and under exertion. The nonstress test does not cause you or your baby any additional exertion. It is evaluating the baby’s heart rate under the most unstressful situation possible.
This test is typically not performed until after the twenty-sixth to twenty-eighth week of pregnancy.
How is a nonstress test performed?
There is virtually no preparation necessary for a nonstress test. Before you begin, the nurse will take your blood pressure.
You will lie in a reclining chair or on a bed or stretcher. Throughout the test, you will have your blood pressure taken several more times.
The nurse will place two belts around your belly. One monitors your baby’s heart rate and the other will monitor any contractions you may be having.
You will be asked to keep a record of when you feel your baby move. Your healthcare provider will later check to see if your baby’s heart rate elevates when he moved.
The exam typically takes approximately twenty minutes. However, if your baby is asleep or not moving very much, they may require you to stay longer.
Normally, your provider will discuss the results with you right away. This can be nice in that you do not have to wait several days in a feeling of emotional limbo.
What does a nonstress test show?
Typically a nonstress test is performed when there is some cause of concern to the life of your baby.
“The goal of a nonstress test is to provide useful information about your baby’s oxygen supply by checking his or her heart rate and how it responds to your baby’s movement.” (Mayo Clinic)
Possible reasons for a nonstress test
- Pregnant with multiple babies with certain complications
- Type 1 diabetes
- Heart disease
- High blood pressure in pregnancy (preeclampsia)
- Past due by two weeks
- History of complications in previous pregnancies
- Decreased fetal movements
- Possible fetal growth problems
- Rh sensitization
- Low amniotic fluid
- After an amniocentesis
The main purpose of the nonstress test is to make sure your baby is getting an adequate amount of oxygen. If there is cause for concern, your care provider may have you have a nonstress test once or twice a week or even every day in some cases.
If the baby’s heart rate raises above a certain level above baseline two or more times for ten or more seconds within the twenty minute time before thirty-two weeks gestation, your baby is considered reactive. He is also considered reactive if the heart rate raises for at least fifteen-seconds more than twice in the twenty minute test. A designation of reactive is a good sign.
If your baby does not meet the criteria for reactive, he is said to be nonreactive. If your baby is at term, your care provider may recommend induction or a c-section. If your baby is not to term, additional testing may be recommended.
A nonreactive designation may not be as serious, however. Causes for a nonreactive result can be cause by your baby being asleep or certain medications that you may be taking. Always make sure you let the health team know of any medications you are taking, including over-the-counter, herbal, vitamins, and alternative medicine.
What are the risks and benefits of having a nonstress test?
A nonstress test is noninvasive which means there is no need to invade your body. There is no need for an IV or any injection. This test is only monitoring and not sending any signals into your body. This is a very safe exam and poses no risk to you or your child.
Psychologically, this test can give reassure a mother and give her peace of mind. However, it can also cause additional stress. Being told you should have a nonstress test may cause you to worry that there may be something seriously wrong with your baby. This is a completely understandable reaction. Remember that doctors often order this test just as a precaution or as a baseline should any additional complications arise.
If the test does show an anomaly or concern, this can also lead to additional anxiety for you. Again, this is perfectly understandable. However, there is much these days that can be done in the case of a child in distress. It is also important to remember that there is a chance that the exam can produce false positives. It is possible that the monitor can detect an issue that is not there.
Like most medical tests, the NST is not a perfect test and can produce false negatives, or miss a problem with your baby.
The NST is a very safe and noninvasive test and while it can cause some anxiety, it can also give you peace of mind and help you prepare if there is a problem with your baby’s cardiovascular system.
If you are in the Denton, TX area and are interested in hiring a doula for your birth experience, contact me today to schedule a free consultation. If you enjoyed this article, you may be interested in checking out my Exams, Tests, Interventions, and Treatments Resource Page.
- “Nonstress Test (NST)”. 2017. Johns Hopkins Medicine. Accessed February 27. http://www.hopkinsmedicine.org/gynecology_obstetrics/specialty_areas/maternal_fetal_medicine/services/antepartum_testing_prenatal_diagnosis_treatment_center/non_stress_test.html.
- “Overview – Nonstress Test – Mayo Clinic”. 2016. Mayo Clinic. http://www.mayoclinic.org/tests-procedures/nonstress-test/home/ovc-20188875.
- Preboth, Monica. 2000. “Practice Guidelines: ACOG Guidelines On Antepartum Fetal Surveillance – American Family Physician”. Aafp.Org. http://www.aafp.org/afp/2000/0901/p1184.html.
- “Special Tests For Monitoring Fetal Health – ACOG”. 2013. The American College Of Obstetricians And Gynecologists. http://www.acog.org/Patients/FAQs/Special-Tests-for-Monitoring-Fetal-Health#test.