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Prenatal tests

Throughout your pregnancy, there are a number of tests that your care provider may recommend to assess your and your baby's health. Not all tests are required by all patients; please discuss any questions you may have about prenatal testing with your care provider.

Personal Health Navigator: What tests to expect when you're expecting

Antenatal blood tests

At your first visit, we will ask you to complete routine blood work. Your health care provider would like to know:

  • Your complete health history
  • Your complete pregnancy history
  • Your blood type
  • Whether you are immune to certain infectious diseases that can be concerning to a pregnant women
  • If you have a history of a sexually transited disease (e.g. HIV, Hepatitis, Syphilis)
  • Common blood conditions that can be managed in pregnancy

Non-stress test (NST)

An NST is a non-invasive 20-minute test to screen how your baby’s heart is beating. An electronic monitor measures the baby’s heart rate and rhythm. An additional monitor will assess your uterus tone and evaluate whether you are contracting.

This test can be done during the end of your second and beginning of your third trimester. The decision to have this test done will be at the discretion of your health care provider. There is no limit to how often this test can be requested. Your health care provider will explain what is being assessed during the testing. Following this test you will be given instructions on when to meet with your health care provider again.

Fetal biophysical profile (BPP)

A BPP is a screening test that assesses how your baby is developing inside your uterus. The test provides your health care provider with a score out of 8. You will be scheduled for an ultrasound in our department where a diagnostic imaging technician will scan your abdomen with an ultrasound tool. We are looking at your baby and will evaluate how well they breathe, move their body and muscles, and volume of amniotic fluid surrounding their body.

Glucose tolerance test (GTT)

Screening for diabetes in pregnancy is done to identify early insulin resistance in pregnancy. The role of insulin in our body is to lower blood sugar levels after eating, and keep it within a healthy range. Insulin resistance means that your body is less sensitive to its own insulin, leading to high blood sugar levels. Insulin resistance in pregnancy can interfere with your child’s growth and development during the pregnancy.

Between 24-28 weeks you will be asked to complete a one-hour sugar (glucose) tolerance test. This routine test will identify your risk of developing diabetes in the pregnancy. You will be instructed to drink a cold orange drink, which is 50 grams of oral glucose (sugar). You will wait one hour, and then have your blood drawn. You will be encouraged to have limited activity in between the time you ingest the drink and the time you have your blood drawn.

A value greater or equal to 11.1 mmol/L confirms the diagnosis of gestational diabetes in your pregnancy. Mmol/L stands for millimoles per liter, the world standard unit for measuring glucose in blood.

If your one-hour test results range from 7.8 – 11 mmol/L you will be asked to complete a two-hour glucose tolerance test. A 75 gram oral glucose (sugar) orange drink is given for the two hour test. You will be encouraged to have limited activity in between the time you ingest the drink and the time you have your blood drawn at the one-hour and two-hour mark following ingestion of the drink. A result below 7.8 is considered normal.

Abnormal results

If any one of these 3 results is above target, you meet the criteria to confirm a diagnosis of gestational diabetes in your pregnancy:

  • Fasting result is greater or equal to 5.3mmol/L; and/or
  • One-hour test result is greater or equal to 10.6mmol/L; and/or
  • Two-hour test result is greater or equal to 9.0mmol/L

To learn more, visit our Diabetes Education page

Group B Streptococcus (GBS) test

GBS is a healthy vaginal bacterium; however, not all women will test positive. GBS does not usually pass to the baby, but if it does, it can cause serious illness. A vaginal-rectal swab will be done around 35-37 weeks to identify whether you have this bacteria present. If our laboratory identifies that the bacteria is present, you will be treated with antibiotics while in labour.

Ultrasound

Toronto Centre for Early Fetal Ultrasound

We perform early-stage, fetal-targeted ultrasound examinations in order to detect potential fetal conditions such as structural anomalies – which are complications that may occur with the development of the fetalskull, brain, spine, abdominal wall, limbs, stomach and bladder – and to detect chromosomal disorders, such as Down's syndrome. Learn more.

Ultrasounds/Echocardiograms

A fetal ultrasound is a procedure that uses high-frequency sound waves to view internal organs and produce images of the human body and your fetus. Learn more.