Third Trimester Pregnancy Tests

Medically Reviewed by Dr. K on 21 April 2021

Table of Contents :

  1. Third Trimester of Pregnancy
  2. Group B streptococcus screening
  3. Electronic fetal heart monitoring
  4. Non-stress test
  5. Contraction stress test
  6. Biophysical profile


Third Trimester of Pregnancy


A wide variety of tests are required for the third and final trimester of pregnancy.


Group B streptococcus screening

At 35 to 37 weeks of birth, vaginal and rectal swabs are obtained to check for group B strep bacteria. While group B strep can be found in up to 30% of healthy women, it is the most common cause of life-threatening infections in newborns and can also contribute to intellectual disability, visual impairment, and hearing loss. Women that test positive are given antibiotics during labour to prevent the infection from spreading to the infant. Instead of testing for strep, your doctor or midwife can decide to treat you when you're in labour if those risk factors emerge.

Electronic fetal heart monitoring


The heart rhythm of the baby is monitored using electronic fetal heart monitors during conception, labour, and childbirth. The fetal heart rate may show whether the baby is well or sick, and it can be measured at some point after 20 weeks.


Non-stress test


This procedure, which is done weekly in certain high-risk deliveries, such as whether a woman is bearing more than one child, has asthma, or has high blood pressure, includes strapping a fetal monitor over the mother's belly and measuring the baby's heart rate when it shifts. It's even used to keep track of babies that are late.


Contraction stress test


A fetal monitor, which is often used in high-risk births, monitors the baby's heart rate in response to contractions induced by oxytocin (Pitocin) or nipple stimulation. The scales are used by doctors to assess how well the baby can handle the discomfort of labour.


Biophysical profile

It can be performed with either an ultrasound or a combination of an ultrasound and a nonstress examination.


Referenced on  10.4.2021

  1. Cohen & Powderly: Infectious Diseases, 2nd edition, 2004.
  2. WebMD Medical Reference from Healthwise: “Electronic Fetal Heart Monitoring."
  3. WebMD Medical Reference from Healthwise: “Nonstress test."
  4. WebMD Medical Reference from Healthwise: “Contraction Stress Test."
  5. Gabbe: Obstetrics-Normal and Problem Pregnancies, 4th edition, 2002.
  6. Stages of pregnancy. (2017).
  7. Third trimester. (2017).

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