Fetal Monitoring Before Delivery: What's It For?

Fetal monitoring before delivery helps to know if the baby is in adequate condition to face the process. Learn more in today's article.
Fetal Monitoring Before Delivery: What's It For?

Last update: 16 April, 2022

Before and during labor, it’s important to know the baby’s state of health, and for this purpose, medical professionals perform a diagnostic test called fetal monitoring before delivery. Do you know what it consists of and what parameters it evaluates? We’ll tell you all about it below. Keep reading!

What is fetal monitoring?

Fetal monitoring is a routine complementary test, which is performed in the last month of pregnancy to evaluate the baby’s vitality. Because at this stage, your child has already reached full term and has completed much of its maturation, it’s possible to infer its state of health through measurements of its movements and heartbeat. For this reason, it’s also known as fetal heart monitoring or cardiotocography.

In general, the normal fetal heart rate ranges from 110 to 160 beats per minute, depending on the time and circumstances. This indicates that the placenta is providing the baby with sufficient oxygen and nutrients and that the baby’s in good health.

This test also evaluates the characteristics of uterine contractions (number, intensity, and duration). In fetal monitoring before delivery, the so-called “false contractions” or Braxton Hicks contractions may appear, which are responsible for preparing the uterus for the moment of birth.

Finally, in the moments before and during labor, fetal monitoring allows the specialist to evaluate the physiological response of the baby to true uterine contractions or labor contractions.

A print out of a fetal monitoring.

When should women undergo fetal monitoring?

As mentioned above, this test is performed at the end of pregnancy, from week 37 onwards. At first, it’s usually performed weekly in low-risk pregnancies. But after the 40th week, the specialist will want to perform it every 3 or 4 days until labor is triggered.

There are specific health conditions for which the physician may advance the start of the monitors or perform them more frequently:

  • Chronic maternal diseases, such as systemic lupus erythematosus, chronic kidney disease, diabetes, arterial hypertension, hyperthyroidism, hemoglobinopathies, and certain cardiac problems.
  • Pregnancy complications, such as preeclampsia, oligohydramnios, moderate or severe isoimmunization, or decreased fetal activity.
  • Prolonged pregnancy (beyond 41 weeks).
  • Premature uterine contractions (from 25 to 37 weeks) or at risk of preterm labor.

It’s important to emphasize that this test should be performed urgently when the mother stops feeling fetal movements or when fetal movements decrease dramatically in frequency. This could indicate the presence of fetal distress and the situation should be monitored immediately.

How is this test performed?

Fetal monitoring before delivery is a painless and non-invasive test that’s performed by means of two ultrasound transducers placed on the skin of the mother’s belly. It’s performed with the woman lying on her back or semi-sitting, depending on the need.

One of the transducers is in charge of capturing the fetal heartbeat, while the other one assesses the uterine activity. Both are connected to a computer that allows the recorded data to be viewed, recorded, and printed on paper.

During the test, the pregnant woman is asked to press a button each time she feels fetal movements. In general, the test lasts 30 minutes, but it can be extended if the baby hasn’t moved at least 5 times during this period.

monitores monitoreo fetal anteparto cardiotocografia

What’s the purpose of fetal monitoring before delivery?

As mentioned above, this test is used to determine fetal vitality, that is, to infer the well-being of the baby inside the uterine cavity. It also serves to corroborate whether the mother has begun labor.

In the event that this test suggests a situation of fetal distress, the specialist may call for the induction of labor or an emergency cesarean section, depending on the condition and severity of the situation.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Colegio Americano de Obstetricia y Ginecología ACOG. (2000). Guía del Colegio Americano de Obstetricia y Ginecología sobre la Vigilancia Fetal Anteparto. Preboth M. Am Fam Physician, 2000 Sep 1;62(5): 1184-1188
  • Colegio Americano de Obstetricia y Ginecología ACOG. (2020) Monitoreo de la frecuencia cardíaca fetal durante el trabajo de parto. Recuperado de: https://www.acog.org/womens-health/faqs/fetal-heart-rate-monitoring-during-labor
  • Instituto Guatemalteco de Seguridad Social. (2014) Monitoreo fetal anteparto. Guías de práctica clínica basadas en la evidencia Nº64.
  • Jiménez, M. (2008). El uso de la monitorización fetal durante el parto en gestantes de bajo riesgo. Matronas Profesión 2008; 9 (2): 5-11
  • Organización Mundial de la Salud. (2011). Fetal monitor. Recuperado de: https://www.who.int/medical_devices/innovation/fetal_monitor.pdf

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.