Pregnancy Screening for Down’s Syndrome, Edwards’ Syndrome, and Patau’s Syndrome in Scotland
1 April 2019 to 31 March 2022

About this release

Revised 24 September 2024: We identified an error in the text explaining quadruple screening, and an error in the text explaining repeat testing following an initial NIPT ‘test failure’ result. Updates have been made to the text in the main report and supporting technical report to correct these. For clarification purposes, we have also added text on Scottish screening programme recommended guidance on the gestation for providing NIPT. The revisions do not affect the data (no numbers have changed). More details on the revisions are provided in Appendix 2 - Publication metadata section of the main report.

This is the first release from Public Health Scotland (PHS) providing information on pregnancy screening for Down's syndrome, Edwards' syndrome, and Patau's syndrome. This release provides information on the coverage of screening (that is, the percentage of eligible women that received screening), screening results, and laboratory screening activity for financial years 2019/20 to 2021/22. More detail on potential developments for future versions of this release are available in the Planned developments section of the main report.

Main points

Among women with a singleton pregnancy booking for antenatal care in Scotland between 1 April 2021 and 31 March 2022:

First line screening

• We estimate that 49,577 women were eligible for pregnancy screening for Down's syndrome, Edwards' syndrome, and Patau's syndrome.
• Of these, 77% (38,114 / 49,577) had any first line screening, with 64% having first trimester combined screening and 13% having second trimester quadruple screening.
• 3.2% (1,021 / 31,846) of women who had combined screening received a higher chance result.
  • 2.6% received a higher chance result for Down's syndrome only.
  • 0.2% received a higher chance result for Edwards' syndrome / Patau's syndrome only.
  • 0.3% received a dual higher chance result for Down's syndrome and Edwards' syndrome / Patau's syndrome. A dual higher chance result occurs when the test cannot clearly distinguish between the chance of the different conditions. It does not mean it is likely that the baby has more than one condition.
• 4.5% (283 / 6,268) of women who had quadruple screening received a higher chance result for Down's syndrome only

Second line screening

• 80% (1,042 / 1,304) of women with a higher chance result from first line screening had non-invasive prenatal testing (NIPT) as a second line screening test.
• 7.9% (82 / 1,042) of women having NIPT received a high chance result, including:
  • 6.1% receiving a high chance result for Down's syndrome only;
  • 1.1% receiving a high chance result for Edwards' syndrome only;
  • 0.6% receiving a high chance result for Patau's syndrome only.
• The percentage of women having NIPT who received a high chance result varied depending on the type of higher chance result from first line screening.

Variation in screening coverage and results

• Screening coverage, and the proportion of first line screening that was combined (rather than quadruple), varied between NHS Board areas.
• The coverage of first line screening was higher among women aged 30-34 years (compared to younger or older age groups); among women living in the least (compared to more) deprived areas of Scotland; and among women with White or Other or mixed ethnicities (compared to South Asian or Black, Caribbean, or African ethnicities).
• The percentage of women receiving a higher chance result from screening increased markedly with increasing maternal age. This reflects the fact that the chance of having a baby with Down's syndrome, Edwards' syndrome, or Patau's syndrome increases with age.

This figure is a bar chart where each bar represents the percentage of women who received a higher chance result from either combined screening or quadruple screening. The bars are grouped into 6 age groups: under 20 years old; between 20 and 24 years (inclusive); between 25 and 29 years; between 30 and 34 years; between 35 and 39 years, and 40 years and over. For both combined and quadruple screening less than 4% of women received a higher chance result in all age groups under 35 years old. For women aged between 35 and 39, 6.3% of those who had a combined screening received a higher chance result and 9.4% of those who had a quadruple screening received a higher chance result. For women aged 40 and over, 16.8% of those who had a combined screening received a higher chance result and 22.6% of those who had a quadruple screening received a higher chance result.

Close

Percentage of women with a higher chance result from first line screening for Down’s syndrome, Edwards’ syndrome, and Patau’s syndrome, 2021/22

Background

Summary information on Down's syndrome, Edwards' syndrome, and Patau's syndrome, and on the pregnancy screening programme for these conditions, is available on NHS Inform. Further relevant information and support are available through Down's Syndrome Scotland, the Support Organisation for Trisomy 13/18 (SOFT-UK), and Antenatal Results and Choices.

Pregnancy screening for Down's syndrome, Edwards' syndrome, and Patau's syndrome is offered to all eligible women as part of NHS antenatal care in Scotland. Screening aims to identify babies who may have one of the three conditions. Whilst all eligible women should be offered screening, it is for individual women to make an informed choice whether or not to accept screening. Detail on the three conditions, the screening pathway, and the different screening tests is available in the Introduction and Appendix 1 of the main report.

The first and second line screening tests assess the chance that a baby has one of the three conditions. Women who receive a high chance result from screening would then be offered the choice of no further testing during pregnancy, or an invasive prenatal diagnostic test that can identify whether a baby definitely does, or does not, have one of the three conditions.

The screening programme changed for women booking for antenatal care in Scotland from 28 September 2020 onwards. For women with a singleton pregnancy, the changes were:

• Extension of first line screening to include combined screening for Edwards' syndrome / Patau's syndrome (with one shared chance result provided for these two conditions) in addition to the existing combined and quadruple screening for Down's syndrome;
• Introduction of NIPT as second line screening for women receiving any higher chance result from first line combined or quadruple screening, with a separate chance result for each of the three conditions provided.

Further information

The next release of this publication will be April 2025.