• Français

Non-stress test (NST)

Maternal Pregnancy Complications


The fetal non-stress test is used to assess the well-being of the fetus during the prenatal period. This examination is recommended when there is a history of pregnancy with complications or when factors that may increase the risk of morbidity/mortality in the fetus are identified during pregnancy. These risk factors may be present in the mother (insulin-dependent diabetes, blood pressure disorders, prolonged pregnancy of more than 41 weeks, twins or multiple pregnancy, etc.) or in the fetus (intrauterine growth restriction, decreased amniotic fluid, birth defects, etc.).

Decreasing fetal movements is also a risk factor. If you notice a decrease in the movements of the unborn child, an assessment must be made by your health care team. An NST will be performed if necessary.

Tests and procedures

Preparing for a non-stress test simply requires the pregnant woman to empty her bladder beforehand. The examination is done in a semi-sitting position or when lying on the left side. In fact, the left lateral position favours fetal-maternal circulation and should be the position of choice throughout pregnancy. Lying flat on the back is not recommended.

The examination is done with the help of a fetal heart monitor. Two sensors are placed on the abdomen: one is used to listen and record the rhythm of the fetus’s heart while the other assesses and records the activity of the uterus (contractions).

The NST normally takes about 20 minutes. Depending on the reactivity of the fetal heart rate, a longer period of time may be required. Throughout the examination, the health care team will read the tracing and extend the session if need be.

The test essentially evaluates the rhythm of the fetal heart and its periodic changes. The heart rate of a fetus is between 110 and 160 beats/minute. It is normal to see them vary between 125 and 150 beats/min, for example. The heartbeat of the fetus, however, should not maintain a consistent rhythm; there should be variability and periods of acceleration.

Treatment and follow-up care

The frequency of the non-stress test depends on the evolution of each pregnancy: it could be requested once during pregnancy or several times a week. Depending on the results obtained, other examinations may be necessary to ensure the well-being of the unborn child.

Resources and useful links

  • Trohaino, Nan H et coll. AWHONN, high-risk & critical care obstetrics. 3e édition, Wolters Kluwer/Lippincott Williams & Wilkins, 2013, 413 p.
  • « Surveillance du bien-être foetal : Directive consensus d’antepartum et intrapartum », Journal d’obstétrique et gynécologie du Canada, vol 29, no 9 (septembre 2007), p. s 3 à s 21.
Page by

Claudia Chavez, inf. clinicienne

About this page
Updated on 1/25/2021
Created on 12/18/2017
Alert or send a suggestion

Every dollar counts!

Thank you for your generosity.

It is thanks to donors such as you that we are able to accelerate research discoveries, to heal more children every year and to continue to offer world-class care.

It is also possible to give by mail or by calling toll-free

1-888-235-DONS (3667)

Contact Us

514 345-4931


© 2006-2014 CHU Sainte-Justine.
All rights reserved. 
Terms of Use,  Confidentiality,  Security


All information contained within the CHU Sainte-Justine site should not be used as a substitute for the advice of a duly qualified and authorized medical practitioner or any other health professional. The information provided on this site is intended for educational and informational purposes only.

Consult your physician if you feel ill or call 911 for any medical emergency.

CHU Sainte-Justine