Guideline No. 456: Prenatal Screening for Fetal Chromosomal Anomalies.

Objective: To review the available prenatal aneuploidy screening options and to provide updated clinical guidelines for reproductive care providers.

Target population: All pregnant persons receiving counselling and providing informed consent for prenatal screening.

Benefits, harms, and costs: Implementation of the recommendations in this guideline should increase clinician competency to offer counselling for prenatal screening options and provide appropriate interventions. Given the variety of available options for prenatal screening with different performance, cost, and availability across Canada, appropriate counselling is of paramount importance to offer the best individual choice to Canadian pregnant persons. Prenatal screening may cause anxiety, and the decisions about prenatal diagnostic procedures are complex given the potential risk of fetal loss.

Evidence: Published literature was retrieved through searches of Medline, PubMed, and the Cochrane Library in and prior to July 2023, using an appropriate controlled vocabulary (prenatal diagnosis, amniocentesis, chorionic villi sampling, non-invasive prenatal screening) and key words (prenatal screening, prenatal genetic counselling). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies written in English and published from January 1995 to July 2023.

Validation methods: The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See Appendix A (Tables A1 for definitions and A2 for interpretations).

Intended audience: Health care providers involved in prenatal screening, including general practitioners, obstetricians, midwives, maternal-fetal medicine specialists, geneticists, and radiologists.

Social media abstract: Non-invasive prenatal screening is the most accurate method for detecting major aneuploidies. It is not universally available in the public health system and has some limitations.

Summary statements: RECOMMENDATIONS.