Second Trimester Screening (STS) Guide

Indicate the racial origin of the pregnant individual. Racial origin information is needed because the concentrations of screening markers have been shown to vary depending on the racial origin. Therefore, a pregnant individual’s screening markers are adjusted based on the racial origin information provided.

Only the broad racial origins listed are needed for screening marker adjustment. The categories on this requisition are not inclusive of the race categories commonly used as social descriptors in Ontario. 

Description / examples for each of the racial origin categories on the requisition:

• Asian: South Asian (E.g. East Indian, Pakistani, Bangladeshi, Sri Lankan, Indo-Caribbean etc.), East/Southeast Asian (e.g. Chinese, Korean, Japanese, Filipino, Indonesian, Thai) descent
• Black: African, Afro-Caribbean descent
• Indigenous: First Nations, Metis, Inuk/Inuit descent
• White: European, Middle Eastern descent (e.g. Arab, Persian, Afhgan, Egyptian, Lebanese, Turkish, Kurdish)
• Other: Another race category or mixed racial origin

Racial origin should be as accurate as possible and should reflect the individual’s ancestral background (which may or may not align with how the pregnant individual identifies), not simply their birth country. This information should be obtained directly from the pregnant individual whenever possible.

Example of question you can ask pregnant individuals:

In our society, people are often described by their race or racial background. For example, some people are considered “White”, “Black”, or “South Asian”. How would you identify or describe your racial background?

Indicate the pregnant individual’s weight, including units (pounds (lbs) versus kilograms (kg)), at the time when this requisition is completed. This information is used for screening marker adjustments. A weight discrepancy of 10 or more pounds (4.6 kilograms) has a significant impact on the risk for trisomy 21 for pregnant individuals with a risk close to the screening cut-off.

Example of questions you can ask pregnant individuals if the weight is not obtained at the time of appointment:

• • What do you think is your current weight? 
  • Do you think the weight your provided is accurate within 5 pounds? 

Indicate the first day of the pregnant individual's Last Menstrual Period (LMP). In the absence of valid ultrasound information, this information will be used to establish the gestational age of the pregnant individual.

Indicate if insulin-dependent Diabetes Mellitus was diagnosed prior to the individual’s current pregnancy. Individuals with insulin-dependent Diabetes Mellitus have been shown to have different concentrations of screening markers compared to those who do not have this diagnosis. Screening marker adjustments must be made to account for these differences.

No screening marker adjustments are made for pregnant individuals with a history of gestational diabetes or preexisting diabetes that is not managed with insulin.

Example of questions you can ask pregnant individuals:

• • Do you have a diagnosis of diabetes? 
  • Was the diabetes diagnosed before the current pregnancy?
  • Do you use insulin to manage the diabetes? 

Indicate if the pregnant individual has smoked or vaped any amount of nicotine at any point in the current pregnancy. Individuals with a history of smoking or vaping nicotine have been shown to have different concentrations of screening markers compared to those who do not have this history. Screening marker adjustments must be made to account for these differences. 

If the requisition does not include information about the smoking or vaping history, the pregnant individual is considered a non-smoker. Due to lack of published data, pregnant individuals exposed to second-hand smoke are considered non-smokers. 

Example of question you can ask pregnant individuals:

Have you smoked any cigarettes or used a nicotine vaping device at any point in the current pregnancy? 

If the pregnancy was conceived using in vitro fertilization (IVF), indicate the egg harvest date and date of birth of the egg donor (either self or non-self). If the egg donor's full date of birth is unknown, indicate the year of birth. If only the year of the donor date of birth is provided, July 1 of the provided year is used as the date.

This information is requested because the age of the egg at the date of delivery influences the screening risk. In addition, screening marker levels vary between IVF and natural conceptions and screening marker adjustments must be made to account for these differences.

Examples of questions you can ask pregnant individuals:

• • Did the current pregnancy happen through in vitro fertilization (IVF)? 
  • What was the egg harvest date?
  • Were your own eggs used for this pregnancy, or was there an egg donor involved? 
  • Do you know the date of birth of the egg donor; at minimum, the year of birth?