Factors that affect the decision to undergo amniocentesis in women with normal Down syndrome screening results: it is all about the age.

Background: Risk for foetal Down syndrome (DS) increases as maternal age increases. Non-invasive screening (maternal serum triple test) for DS is routinely offered to pregnant women to provide risk estimates and suggest invasive amniocentesis for definitive pre-natal diagnosis to high-risk women.

Objective: We examined women's decision process with regard to pre-natal screening, and specifically, the degree to which they take into account triple serum screening results when considering whether or not to undergo amniocentesis.

Design: Semi-structured phone interviews were conducted to assess recall of DS screening results, understanding of risk estimates and their effect on women's decision whether to undergo amniocentesis. The study included 60 pregnant Israeli women (half younger than 35 and half advanced maternal age - AMA), with normal DS screening results and no known ultrasound abnormalities.

Results: Age appeared to determine the decision process. The vast majority of AMA women had amniocentesis, many of them before receiving their DS screening results. Most AMA participants knew that their risk estimate was 'normal', but still considered themselves at high risk due to their age. Procedure-related risk (miscarriage) and other factors only had a minor effect on their decision. A minority of younger women had amniocentesis. Younger women mentioned procedure-related risk and having normal screening results as the main factors affecting their decision not to have amniocentesis.

Conclusion: Age 35 is an anchor for the pre-determination regarding performing or avoiding amniocentesis. AMA women mention 'age' as their main reason to have amniocentesis and considered it an independent risk factor.