Prenatal screening is a type of routine testing that is available to all pregnant patients in Ontario. It is a non-invasive way to determine the chance to have a pregnancy with Down syndrome and trisomy 18. This chance is determined by collecting maternal and pregnancy information through ultrasound and/or maternal bloodwork. There are no risks associated with this type of testing. It is important to note that the results of prenatal screening are not diagnostic and will not give definitive answers about Down syndrome or Trisomy 18.
Prenatal screening is completely optional and can be ordered by your health care provider.

If you aren't sure how far along you are, calculate your estimated due date using the Society of Obstetricians and Gynaecologists of Canada due date calculator. 

Deciding if prenatal screening is right for you

No one can tell you if prenatal screening is right for you. It is a personal decision and there is no right or wrong answer. All prenatal screening is optional.

You should ask yourself:

• How important is it for you to know if there is an increased chance of a chromosome change that could affect your baby's health and development?
• If your screen result is positive, how likely are you to consider more testing?
• How useful would it be for you to know about a chromosome change before your baby's birth to prepare?
• What are your thoughts about continuing or ending your pregnancy if your baby has a chromosome change?
• How would knowing or not knowing affect you emotionally throughout the pregnancy?

If you decide that you don't want to have these tests, your health care provider will continue to provide you with care. You should still have an ultrasound in the first and second trimesters of your pregnancy.

These ultrasounds will give you more information about:

• how far along your pregnancy is;
• how many babies you are carrying; and
• whether there are concerns with the baby's growth and anatomy.

Invasive diagnostic testing

If you did not have prenatal screening, if your prenatal screening results are not reassuring, or you have other concerns, you may consider having invasive diagnostic testing to get more definitive information. Talk to your health care provider if you would like to be referred for more information.