Prenatal screening tests in Canada

What is offered, and who decides

Every pregnant person in Canada is offered prenatal genetic screening, and the Society of Obstetricians and Gynaecologists of Canada is explicit that it should be offered to all women. What is not national is the test menu. Health care is delivered provincially, so the name of the screening test, the gestational window, the laboratory and the funding rules all change at the provincial border. Ontario's programme is used below as a worked example because it publishes its criteria openly; if you are in another province, the shape will be similar but the labels and cut-offs will not match exactly.

Two things are consistent across the country:

• Screening tells you a chance, never a diagnosis. A positive screen requires a diagnostic test to confirm.
• A detailed anatomy ultrasound at 18 to 22 weeks is offered regardless of which genetic screening you choose, or whether you choose any.

The genetic screening options

Enhanced First Trimester Screening (eFTS)

Ontario's publicly funded first trimester option combines a nuchal translucency ultrasound with a blood test, and it must be done between 11 weeks 2 days and 13 weeks 3 days. The ultrasound comes first, the blood draw second. It screens for trisomy 21 and trisomy 18 only — in Ontario it does not screen for trisomy 13. Family doctors, obstetricians, midwives and nurse practitioners can all order it, and you can arrange it through a walk-in clinic if you do not have a family doctor.

eFTS is not appropriate if you already have a low-risk NIPT result, if you are waiting on NIPT results, if you had a vanishing twin, or if you are carrying more than one baby.

Second Trimester Screening (STS)

If the first trimester window has passed or a nuchal scan is not available, the publicly funded second trimester blood test can be done from 14 weeks to 20 weeks 6 days. It measures four proteins made by the pregnancy and, like eFTS, reports on trisomy 21 and trisomy 18. No ultrasound is required, though having one improves accuracy. It is not used for multiple pregnancies.

Non-invasive prenatal testing (NIPT)

NIPT is the most accurate prenatal screening test available and can be done from 9 or 10 weeks right through to the end of pregnancy. It screens for trisomy 21, trisomy 18 and trisomy 13, with optional screening for sex chromosome differences, which is less accurate and should be discussed first.

The catch is funding. NIPT is available to everyone, but it is only publicly funded if you meet a specific criterion at the time of the blood draw. Ontario updated those criteria on 30 March 2026. The Category I criteria, which any physician, midwife or nurse practitioner can order against, are:

• a multiple marker screen (eFTS or STS) that is positive for aneuploidy
• age 40 or older at the expected date of delivery — or, for IVF pregnancies, an oocyte age of 39 or older at retrieval, whether your own egg or a donor egg
• a previous pregnancy or child with trisomy 21, 18 or 13
• a twin pregnancy with cardiac activity confirmed in both fetuses
• a nuchal translucency measurement of 3.5 mm or more

An NT of 3.5 mm or more now also triggers a recommendation for prompt referral to Genetics or Maternal-Fetal Medicine regardless of whether NIPT is ordered or what it shows, because a thickened NT is associated with genetic conditions and structural anomalies that NIPT does not detect. Do not wait for the NIPT result before accepting that referral.

Category II criteria — ultrasound anomalies, cystic hygroma and certain soft markers — must be ordered by a genetics or maternal-fetal medicine specialist. In the March 2026 update, isolated absent or hypoplastic nasal bone and an isolated increased nuchal fold of 6 mm or more qualify, two or more low-likelihood soft markers qualify together, and choroid plexus cysts were removed from the list entirely.

If you meet none of the criteria, NIPT is not an insured service and you pay out of pocket, or claim it through private insurance if your plan covers it.

Ultrasound, and the rest of the routine tests

Two ultrasounds sit alongside the genetic pathway, and you can have either of them whatever you decided about genetic screening.

The 18 to 22 week detailed anatomy ultrasound examines how the baby's internal organs and structures are developing — heart, brain, kidneys, spine, arms and legs — along with the baby's size for dates, position and activity, the volume of fluid, the location of the placenta and umbilical cord, and your own cervix, uterus, ovaries and bladder. Determining the baby's sex is not one of its goals, though it is often visible. Expect to be asked to drink a litre of water beforehand.

It can be arranged by a doctor, nurse practitioner or midwife. You will be given a requisition, and depending on the practice you may be asked to book the appointment yourself rather than having it booked for you.

Alongside the genetic pathway, routine care includes:

• Blood group, rhesus status and antibody screen, with Rh immune globulin offered if you are Rh negative.
• Hepatitis B surface antigen and HIV screening, offered as part of routine prenatal care and ideally in the first trimester.
• Gestational diabetes screening at 24 to 28 weeks for everyone. The first step is a glucose challenge: a sugary drink, then a blood sample an hour later, with no fasting required and no restriction on the time of day. If that reading is high, a second fasting test follows. If you have risk factors — age over 35, pre-pregnancy BMI over 30, family history, PCOS, a previous large baby or previous gestational diabetes — you are tested earlier and retested later.

What happens if you decline, or do not qualify

Declining screening is a legitimate choice and does not affect the rest of your care. Many people decline genetic screening but accept the anatomy scan, which looks at structure rather than chromosomes.

If you do not meet the funding criteria for NIPT, you have three reasonable options: take the publicly funded eFTS or STS and only move to NIPT if the result comes back positive, which then qualifies you for funding; pay for NIPT privately; or decline genetic screening altogether. Starting with the funded test and escalating is the route the system is designed around, and it means most people who need NIPT end up getting it funded.

A positive screen leads to a discussion about diagnostic testing — chorionic villus sampling or amniocentesis — which is the only way to be certain. Those tests carry a small risk of miscarriage and are always a choice.

Where to get help

Prenatal Screening Ontario, run through the BORN Ontario registry at the CHEO Research Institute, staffs an information line with genetic counsellors and screening specialists on 1-833-351-6490, Monday to Friday, 9:00 am to 3:00 pm EST. They cannot order tests, but they will explain your options. Outside Ontario, ask your midwife, family doctor or obstetrician which provincial programme applies and what its funding criteria are — the answer genuinely differs. The Society of Obstetricians and Gynaecologists of Canada publishes plain-language material on routine prenatal tests at pregnancyinfo.ca.