Do maternal screening tests provide psychologically meaningful results? Cognitive psychology in an applied setting

Abstract

Prenatal screening tests such as maternal serum screening for Down Syndrome, Edward's Syndrome and neural tube defects are now a routine feature of antenatal care. These tests assess the probability that the foetus has one of these conditions, and those at high risk are offered further testing. This paper seeks to examine whether the screening tests provide a benefit to women being screened. Cognitive psychology research suggests that our reasoning based on probabilistic information is not usually consistent with the formal laws of mathematics. Instead, we may rely on reasoning heuristics such as ‘representativeness’. Research has consistently shown that, when provided with all information relevant to a screening test, we tend to either over‐ or underestimate the probability that the screening result indicates a ‘true’ as opposed to ‘false’ positive result. Applied research into the experience of prenatal screening has used very different methodologies, but the findings are consistent with those from lab‐based cognitive psychology research. The implications may be that probabilistic screening information does not provide useable information and therefore does not promote informed choice. Tests may also fail to offer reassurance, or offer false reassurance.