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Prenatal Screening Performance

PSO is housed within BORN Ontario. BORN is Ontario's prescribed perinatal, newborn and child registry with the role of facilitating quality care for families across the province. BORN collects, interprets, shares and rigorously protects high-quality data essential to making Ontario one of the safest places in the world to have a baby. With the help of our external partners,  prenatal screening and outcomes data is collected in the BORN Information System (BIS), enabling PSO to assess the performance of prenatal screening for pregnant individuals in Ontario through comparison of screening results to diagnostic cytogenetic (chromosome testing) results and birth outcomes.

Please note that the timelines for the data holdings presented below vary; the specific timeline can be found within the data notes.

What was the performance of prenatal screening for singleton pregnancies?

Table 1. Performance of Multiple Marker Screening (MMS) for singleton pregnancies.
Screening type Chromosome
difference		 Sensitivity 
(95% CI)		 Specificity
(95% CI)		 PPV
(95% CI)		 NPV
(95% CI)		 FPR 
(95% CI)		 FNR
(95% CI)
eFTS T21

88.23

(86.38, 89.91)

93.94

(93.87, 94.01)

3.90

(3.69, 4.13)

99.97

(99.96, 99.97)

6.06

(5.99, 6.13)

11.77

(10.09, 13.62)
STS T21

87.18

(77.68, 93.68)

91.38

(91.08, 91.68)

2.22

(1.73, 2.80)

99.97

(99.94, 99.98)

8.62

(8.32, 8.92)

12.82

(6.32, 22.32)
eFTS T18

87.31

(83.61, 90.43)

99.71

(99.70, 99.73)

20.11

(18.23, 22.08)

99.99

(99.99, 99.99)

0.29

(0.27, 0.30)

12.69

(9.57, 16.39)
STS T18

S

(45.13, 86.14)

99.38

(99.30, 99.46)

6.22

(3.53, 10.06)

99.98

(99.96, 99.99)

0.62

(0.54, 0.70)

S

(13.86, 54.87)

Data Source: BORN Ontario, 1 September 2016 - 31 March 2023 by EDD

1. Data were extracted from the BORN Information System (BIS) on 1 June 2024. Note that data submission to the BIS is both voluntary and open to updates and amendments. This table represents a snapshot of the BIS on the date of data extraction.

2. The cohort timeline was defined by estimated date of delivery.

3. S = point estimate suppressed when confidence interval >20%.

4. Only singleton pregnancies were included in this analysis.

5. Only pregnancies with a valid MMS result and cytogenetic result were included in this analysis. Outcome data were supplemented using clinical examination data from the BORN Information system (BIS) for negative results for T21, and 18 when cytogenetic results were missing.

6. "eFTS" includes both "4-marker eFTS" and "5-marker eFTS."

7. The screen-positive cut-off for STS (MSS Quad) for T21 changed over the timeline of this analysis from 1/200 before April 2020 to 1/350 after April 2020. The data presented here are with the 1 in 350 cut-off applied throughout the entire timeline of these data.

8. MMS screens were performed by the MMS Laboratories at Mount Sinai Hospital or North York General Hospital or Trillium Health Partners.

9. BORN Ontario strives to better understand how our data can be used to inform health system partners on the intersection between social determinants of health, indigeneity, and perinatal and child health outcomes. This table includes data that may or may not support reflections on indigeneity and health equity. We cannot conclusively or accurately identify the extent to which BORN data reflect indigeneity and equity-deserving groups. This pursuit is ongoing, and we appreciate your support and ideas related to enabling our efforts in pursuit of more equitable outcomes and programming.

Table 2. Performance of OHIP-funded Non-Invasive Prenatal Testing (NIPT) for singleton pregnancies.
Chromosome
difference 		  Sensitivity
(95% CI)		 Specificity
(95% CI)		 PPV
(95% CI)		 NPV
(95% CI)		 FPR
(95% CI)		 FNR
(95% CI)
T21 

99.13

(98.48, 99.55)

99.91

(99.89, 99.94)

96.32

(95.20, 97.24)

99.98

(99.97, 99.99)

0.09

(0.06, 0.11)

0.87

(0.45, 1.52)
T18

95.76

(92.98, 97.66)

99.97

(99.96, 99.99)

95.18

(92.29, 97.22)

99.98

(99.96, 99.99)

0.03

(0.01, 0.04)

4.24

(2.34, 7.02)
T13

92.52

(85.80, 96.72)

99.95

(99.93, 99.97)

76.74

(68.49, 83.73)

99.99

(99.97, 99.99)

0.05

(0.03, 0.07)

7.48

(3.28, 14.20)

Data Source: BORN Ontario, 1 September 2016 - 31 March 2023 by EDD

1. Data were extracted from the BORN Information System (BIS) on 1 June 2024. Note that data submission to the BIS is both voluntary and open to updates and amendments. This table represents a snapshot of the BIS on the date of data extraction.

2. The cohort timeline was defined by estimated date of delivery.

3. Only singleton pregnancies were included in this analysis.

4. Only pregnancies with a valid NIPT result and cytogenetic result were included in this analysis. Outcome data were supplemented using clinical examination data from the BORN Information system (BIS) for negative results for T21, 18 and 13 when cytogenetic results were missing.

5. OHIP-funded NIPT screens were performed by Dynacare or LifeLabs.

6. BORN Ontario strives to better understand how our data can be used to inform health system partners on the intersection between social determinants of health, indigeneity, and perinatal and child health outcomes. This table includes data that may or may not support reflections on indigeneity and health equity. We cannot conclusively or accurately identify the extent to which BORN data reflect indigeneity and equity-deserving groups. This pursuit is ongoing, and we appreciate your support and ideas related to enabling our efforts in pursuit of more equitable outcomes and programming.

How many pregnancies had a screen positive MMS or a high-risk NIPT result?

  • Most pregnancies with MMS had a screen negative result.
  • Of the pregnancies with NIPT (publicly-funded and self-paid):
    • There were more high-risk results overall for publicly-funded NIPT (4.3%) compared to self-paid NIPT (1.3%). This is because pregnancies having publicly-funded NIPT had an increased a priori chance to have a chromosome aneuploidy compared to the general population chance.
    • The number of high-risk NIPT results overall for sex chromosome aneuploidies (SCAs) was similar for publicly-funded (0.5%) and self-paid NIPT (0.4%). 

Figure 6. Screen positive rates for MMS and high-risk rates for OHIP-funded and self-paid NIPT.
Population MMS OHIP-funded NIPT Self-paid NIPT
Screen positive T21 6.1%: 18,725 pregnancies had a screen positive MMS result for T21.     
Screen positive T18 <0.5%: 843 (0.3%) pregnancies had a screen positive MMS result for T18.     
Screen positive T21 AND T18 <0.5%: 627 (0.2%) pregnancies had a screen positive result for T21 AND T18    
Screen negative 93.2%: 286,517 pregnancies had a screen negative MMS result.    
No screening result <0.5%: 767 (0.2%) of pregnancies had no screening result    
High-risk T21 only   2.7%: 920 pregnancies had a high-risk NIPT result for T21 only. 0.6%: 175 pregnancies had a high-risk NIPT result for T21 only.
High-risk T18 only   0.8%: 256 pregnancies had a high-risk NIPT result for T18 only. <0.5%: 57 (0.2%) pregnancies had a high-risk NIPT result for T18 only.
High-risk T13 only   0.3%: 111 pregnancies had a high-risk NIPT result for T13 only. <0.5%: 36 (0.1%) pregnancies had a high-risk NIPT result for T13 only.
High-risk SCA only   0.5%: 187 pregnancies had a high-risk NIPT result for SCA only. 0.4%: 130 pregnancies had a high-risk NIPT result for SCA only.
Low-risk   93.6%: 31,856 pregnancies had a low-risk NIPT result. 97.3%: 30,184 pregnancies had a low-risk NIPT result.

Data source: BORN Ontario, 1 April 2020 - 31 March 2023​

 

Definition of indicator: MMS screen positive rate for singleton pregnancies with a screen at MSH, NYGH, and THP stratified by modality​

Notes:

1. Data were extracted from the BORN Information System (BIS) on June 1, 2024. Note that data submission to the BIS is both voluntary and open to updates and amendments. This table represents a snapshot of the BIS on the date of extraction.​

2. Fiscal year was defined by pregnant person estimated date of delivery. Each fiscal year ranges from April 1 to March 31, inclusive.​

3. The cohort timeline was defined by pregnant person date of delivery.​

4. Only singleton pregnancies were included in this analysis.

 

Definition of indicator: NIPT high-risk rates by funding status for singleton pregnancies with a screen at Dynacare or LifeLabs

Notes:

1. Data were extracted from the BORN Information System (BIS) on June 1, 2024. Note that data submission to the BIS is both voluntary and open to updates and amendments. This table represents a snapshot of the BIS on the date of extraction.​

2. Fiscal year was defined by pregnant person estimated date of delivery. Each fiscal year ranges from April 1 to March 31, inclusive.​

3. The cohort timeline was defined by pregnant person date of delivery.​

4. Only singleton pregnancies were included in this analysis.

5. Pregnancies with 'no results' and 'high risk triploidy' are not presented here.

6. BORN Ontario strives to better understand how our data can be used to inform health system partners on the intersection between social determinants of health, indigeneity, and perinatal and child health outcomes. This table includes data that may or may not support reflections on indigeneity and health equity. We cannot conclusively or accurately identify the extent to which BORN data reflect indigeneity and equity-deserving groups. This pursuit is ongoing, and we appreciate your support and ideas related to enabling our efforts in pursuit of more equitable outcomes and programming.

How many high-risk NIPT results were there for each OHIP clinical funding indicator?

Table 4. NIPT volumes and results for common OHIP clinical funding indicators.
Indication for funding Number of screens Number reported as high-risk T21 only (%) Number reported as high-risk T18 only (%) Number reported as high-risk T13 only (%) Number reported as high risk SCA difference only (%) Low risk (%)
Maternal age 40 and over at EDD only 12,627 

 301

(2.4%)

125

(1.0%) 

40

(0.3%) 

83

(0.7%) 

 11,707 (92.7%)
Positive multiple marker screen only  13,624

 352

(2.6%)

48

(0.4%) 

 27

(0.2%)

35

(0.3%) 

 12,949 (95.0%)
Increased nuchal translucency only  698

 90

(12.9%)

 25

(3.6%)

19

(2.7%) 

31

(4.4%) 

 511 (73.2%)
Previous pregnancy with trisomy 21, 18 or 13 only  1,661

 11

(0.7%)

S

(S) 

 S

(S)

 S

(S)

 1,613 (97.1%)
Fetal anomalies only 668 

13

(1.9%) 

6

(0.9%) 

S

(S) 

 S

(S)

 627 (93.9%)
Aneuploidy risk greater than a positive multiple marker screen result only 1,969 

 23

(1.2%

7

(0.4%) 

 S

(S)

8

(0.4%) 

  1,907 (96.9%)
Increased risk for sex-linked condition/DSD only 208

 0

(0%)

0

(0%) 

0

(0)% 

 S

(S)

 202 (97.1%) 
Multiple indications 2,595

 130

(5.0%)

44

(1.7%)

18

(0.7%) 

22

(0.8%) 

 2,340 (90.2%) 

Key Messages:

  • An 'increased NT only' is associated with the highest overall positive rate (23.6%) for T21, T18, T13, and SCA combined.
  • A 'previous aneuploidy only' is associated with the lowest overall positive rate (0.7%) for T21, T18, T13, and SCA combined. 

 

Data source: BORN Ontario, 1 April 2020 - 31 March 2023

Definition of indicator: NIPT volume by clinical indication for OHIP funding for singleton pregnancies with a screen at Dynacare or LifeLabs.

Notes:

1. Data were extracted from the BORN Information System (BIS) on June 1, 2024. Note that data submission to the BIS is both voluntary and open to updates and amendments. This table represents a snapshot of the BIS on the date of extraction.

2. Fiscal year was defined by pregnant person estimated date of delivery. Each fiscal year ranges from April 1 to March 31, inclusive.

3. The cohort timeline was defined by pregnant person date of delivery.

4. Only singleton pregnancies were included in this analysis.

5. S = data suppressed due to small cell size, or, suppressed to prevent back-calculation of another cell suppressed due to small cell size.

6. Pregnancies reported as “no results” and "high risk triploidy" are included in the total pregnancies with NIPT.

7. Pregnancies reported as “high risk for multiple conditions” cannot be displayed due to small cell sizes but are included in the total pregnancies with NIPT.

8. A 'previous aneuploidy' is defined as a previous pregnancy or child with T13 or T18 or T21.

9.BORN Ontario strives to better understand how our data can be used to inform health system partners on the intersection between social determinants of health, indigeneity, and perinatal and child health outcomes. This table includes data that may or may not support reflections on indigeneity and health equity. We cannot conclusively or accurately identify the extent to which BORN data reflect indigeneity and equity-deserving groups. This pursuit is ongoing, and we appreciate your support and ideas related to enabling our efforts in pursuit of more equitable outcomes and programming.

How long did it take for MMS and NIPT results to be reported to the ordering practitioner?

Be sure to check the Dynacare and LifeLabs websites for the most up-to-date turn-around times for NIPT results.

 

Data source: BORN Ontario, 1 April 2020-31 March 2023​

 

Definition of indicator: NIPT and MMS turnaround time for singleton pregnancies with an NIPT screen at Dynacare or LifeLabs and an MMS screen at MSH, NYGH, or THP.​

​

Notes:

1. Data were extracted from the BORN Information System (BIS) on June 1, 2024. Note that data submission to the BIS is both voluntary and open to updates and amendments. This table represents a snapshot of the BIS on the date of extraction.​

2. Fiscal year was defined by pregnant person estimated date of delivery. Each fiscal year ranges from April 1 to March 31, inclusive.​

3. The cohort timeline was defined by pregnant person date of delivery.​

4. Only singleton pregnancies were included in this analysis.

4 days for MMS results
Median number of days from MMS blood collection to report date.

8 days for NIPT results
Median number of days from NIPT blood collection to report date.

Figure 7. Median turn-around times from blood collection date to report date for MMS and NIPT.

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Contact Us

Prenatal Screening Ontario 
CHEO Research Institute 
Centre for Practice-Changing Research Building 
401 Smyth Road 
Ottawa, ON K1H 8L1

Information line
Phone: 613-737-2281
Toll-Free: 1-833-351-6490

Monday to Friday, 9:00 AM to 3:00 PM EST

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