A non-stress test is a popular test for women expecting a child. One may require it if one is overdue or has had complications at the time of pregnancy and childbirth. The doctor may propose the test, for less than regular or usual fetal movements. The test is a simple and non-invasive one. It focuses on checking your baby’s health.
The test further records the movement, contractions, and heartbeat of the baby. There are changes in heart rhythm when the baby moves from the resting state, or at the time of contractions during labor. When active, your baby’s heart should beat faster – just like an adult humans does. The non-stress test offers the guarantee that the child is healthy and can receive enough oxygen.
It is known as a non-stress test because it does not bother the baby. The doctor does not use medicines to make the baby move. Additionally, the NST or nonstress test records what is naturally being done by the baby.
How The Test is Performed
The non-stress test is safe for both mother and child. It involves attaching two belts around the belly as the mother lies down. While one belt measures the baby’s heartbeat, the other one measures contractions. When the child kicks or moves, a button needs to be pressed so doctors can see how the baby’s heartbeat changes while there is movement. The test lasts for a duration of twenty minutes.
If the child is sleeping, the nurse can wake up the baby by moving the belly, ringing a bell or even trying acoustic stimulation. A normal non-stress test indicates the baby is receiving enough oxygen and performing well. In case results are not usual, further testing may be required by the doctor.
If the baby does not move at the time of the non-stress test, there is no cause for worry, however, Mothers with abnormal non-stress test results also end up having healthy babies. It may be that the baby is sleeping through the entire process. The test does not check movement but evaluates the heartbeat’s reactivity. There could be appreciable movement at the time of the test or not.
Testing During Pregnancy
Women can opt for non-stress testing every week or bi-weekly after 28 weeks if there is a high-risk pregnancy. Before 28 weeks, the test is not accurate. One may require only a single isolated nonstress test if the child is not moving well. The test may be often needed depending on the situation. Asking your doctor for advice is the right approach.
Importance of an NST
At the close of pregnancy, a key component of prenatal health is monitoring the baby’s well being. While this is the purpose behind the prenatal care, some help may be needed for medical diagnosis and evaluation. This is where late pregnancy-based fetal surveillance is extremely useful. NST is one of the most commonly based tests carried out.
This test can be carried out in the late pregnancy stages. It is frequently applied when the mother has gone past her assigned due date to ensure the well-being of the fetus. In some cases, it works as a precaution after issues in an earlier pregnancy or on account of high-risk factors like intrauterine growth retardation, diabetes and much more.
The test is most commonly carried out between weeks 38 and 42. It can be used early at the start of the third trimester as well. It needs to be carried out daily, depending on the reason for the NST.
The test results are given as reactive and non-reactive, Sometimes, the babies don’t cooperate at the time of testing or move as per the requirement. Mothers may be offered a drink containing sugar to perk the child up. In case the baby does not move sometimes, a loud acoustic stimulus may be used to startle the child into moving. Babies can and do sleep in utero, so it is possible that movements may not be recorded as a result of that.
Mostly, the test is not a risky one. This is not an invasive test and does not need blood samples or invasive exams. The biggest risk includes data misinterpretation and ultrasound exposure. If one has concerns, be sure to check with the practitioner before undergoing the test. This reassures individuals about how they are working to minimize risks for the mother and the baby.
There are 2 possible alternatives to the NST – stress testing or the biophysical profile. Alternatives may not be suitable, so there is an option of delaying the non-stress test.
After an NST
Post the NST, if the baby is not responsive, one may have to opt for a biophysical profile, induction or stress test. The procedure and reason as to why this test is done vary across practitioners. If there are questions about the test, when it is carried out, how often it must be repeated etc. you need to speak up and ask questions. When pregnant, the healthcare services provider can do many tests to check the well-being of the baby. This tests can be carried out at any point in the pregnancy.
Tests may be required for ladies with high-risk pregnancies or those with accompanying health conditions like diabetes. Additionally, there may be complications in a previous pregnancy promoting the NST. Such a test may also be performed when the pregnancy exceeds forty weeks and the baby and is overdue. The tests can be carried out more than a single time so providers can track the baby's progress across time. This helps providers to find solutions or even detect problems. Talking to the provider about results and tests is critical. A healthy baby will have a heart rate that rises periodically. During the NST, the provider also checks if the heart rate of the baby shoots rapidly while moving or resting. No medicines are received for such a test.
In case the heart rate of the baby does not shoot up on its own, the mother may be asked to rub the belly to wake up the sleeping baby. Additionally, the mother will be hooked to a monitor for studying fetal rate, which is the heart monitor for the baby. In case the baby’s heart rate shoots up over a period of time, the test results will be mostly normal. NST results that work reactively mean the heart rate of the baby went up in a normal way. Non-reactive test results indicate the baby’s heart rates did not climb up enough. In case the heart rate doesn't shoot up, more tests are needed.
Another term is the categorizing as one of three. 1 indicates the normal results are there. 2 stands for further testing/observation is required. A category 3 test result means the delivery should be instant. If the NST results are abnormal, contraction stress tests are needed. This test helps providers to ascertain how well the baby will perform up to the point of labor. Labor causes baby stress. Each contraction means babies get less blood, nutrients, and o2 for some time. For some children, this isn't an issue. But some babies face problems. A CST showcases how the baby’s body reacts to labor contractions.
Biophysical Profile: NST With Ultrasound
Biophysical profile refers to an NST along with an ultrasound. In case the results of NST are nonreactive, a biophysical profile may be carried out. The biophysical profile checks out the body-tones, breathing, baby movements and the consequences of the non-stress test. The biophysical profile looks at the amniotic fluids, surrounding the fetus. The profile tests can be normal, deviated or lacking in clarity. If the results are not clear, the test may require being repeated. Abnormal results mean the baby should be immediately delivered.
A modified biophysical profile is also an ultrasound NST. The test studies the amount of amniotic fluid the womb contains.
The modified biophysical profile takes less time. A doctor may opine that the modified biophysical profile is enough for checking the baby’s health. Fetal NST tests are used in pregnancy to inactively monitor the heart-rate of the child. This tells the healthcare providers about the baby’s health.
What NST Indicates About the Baby’s Health
NST informs health care providers about the total number of beats and the baby's heart rate pattern. It tells a lot more about that which is taking place in utero. A normal fetal heart rate ranges from 110 to around 160 beats per minute. In case the heart rate drops below 110, it is the sign is the baby is in distress. As it goes beyond 160 BPM, this is an indication the child is facing a difficulty responding to the stress.
The ability of the heart to react to the physical activity indicating health status. When one exercise, the heartbeat shoots up and in the event that one rests, it plummets. This takes place between the fetus and the result is that healthcare practitioners check for variance in the heart rate of the baby to determine the child’s health. The greater the variation in the heart rate of the fetus, the greater the assurance that the baby is healthy. If the heart rate is minimally variable, it is an indication the baby is facing an issue while responding to surroundings and suffer from organ and heart function.
Reasons for an NST
NST is done before labor and before any stress on the fetus. Apart from assessing the health of the baby, there are numerous reasons why the doctor may want to carry out the nonstress test. This includes if you are exceeding your due date and need to be monitored. NST is also essential for monitoring post the induction of labor. In case the pregnancy is made further difficult by increased risk conditions like diabetes and high BP, NST may be required. In case there is reduced fetal growth or less fetal movements, one may require a non-stress test. If one has had issues in previous pregnancies, the non-stress test may be carried out.
An NST can be carried out if the baby can be sensed to be moving infrequently as against usual movements, women are overdue, mothers are at high risk for other reasons or the placenta is not functioning well enough. The test shows if the baby is facing oxygen deprivation due to the placentas or umbilical cord issues.
There can also be other risks causing fetal distress.
Risks or Side Effects of NST
An NST is an evaluation which is noninvasive with zero side effects or risks to the mother or child. NSTs are performed post 28 weeks of gestation. Prior to 28 weeks, the fetus is not adequately developed to respond to test protocols. The primary aim of this test is measuring the fetal heart rate reacting to movements. Healthy infants have increased heart rate with movement; the heart rate falls as a result. The idea behind NST is that enough O2 is needed for heart rate and fetal activity to fall within a normal range.
When oxygen levels are low, the fetus does not normally respond. Fewer levels of oxygen are caused by issues such as placenta oriented or umbilical cord issues. A reactive NST indicates that oxygen and blood flow for the fetus is enough. A nonreactive MST requires additional and extra testing to assess if the results are on account of poor oxygenation. There may be additional reasons for fetal nonreactivity such as maternal prescription and/or non-prescribed drugs and sleep patterns. Also called the fetal heart rate monitoring test, NST is essential for pregnant women to check on the baby’s health.
Additionally, the baby’s health is evaluated and other complications are corrected before birth. The procedure provides useful health information about the baby and whether he or she is receiving enough oxygen supply within the womb. This involves checking the baby’s heart rate and reactions to the fetal movements.
The doctor will also recommend an NST if the baby is not moving as frequently as before if one is past the due date. If a non-functioning placenta or condition like gestational diabetes or preeclampsia is suspected, the NST may be carried out. It may also be performed if the baby is small for the gestational age.
Do note that a reactive outcome is far likely to be an accurate one than a nonreactive one. If one has an NST with an initial nonreactive result and then with a reactive result, the second nonstress test is considered the more reliable one. For those taking an NST, it is important to note that the baby is in a healthy state. The NST may also be considered when there is too much or too little amniotic fluid in the womb. Additionally, a procedure such as the external cephalic vision or third-trimester amniocentesis may also be tested. The doctor may order an NST to ensure the baby is performing well. If one is past the due date, and the practitioner wants to know how the baby is holding up at the time of extended stay in the womb, the NST may be carried out.
For understanding the NST results, note that if the fetal heartbeat is faster at a minimum of 15 beats per minute over the resting rate, while there is a movement for at least 15 seconds on two separate
occasions during the span of the test, the result is reactive or normal. A normal result means the baby is doing well presently. The test may need to be repeated each week until the baby is born.
If the baby’s heartbeat is not fast during movement, or the baby does not move beyond 90 minutes, nonreactive results occur.
A nonreactive result does not mean there is a problem. It just means the test did not provide adequate information and it is needed to take again in an hour along with other tests like a biophysical profile or contraction stress test. If the doctor, however, assesses that the baby lack oxygen or there are problems with the placenta, the decision to induce labor may be taken. Thus, non-stress tests can pave the way for medical action required and preserve the health of the child.