Prenatal assessment of fetal health is routinely offered throughout pregnancy to ensure that the most effective management can be provided to maintain fetal and maternal well-being. Currently, invasive testing is used for definitive diagnosis of fetal aneuploidy, which is associated with a 1% risk of iatrogenic fetal loss. Developing non-invasive prenatal testing (NIPT) is a key area of research and methods to increase the level of cell-free fetal DNA (cffDNA) within the maternal circulation have been discussed to improve accuracy of such tests. In this study, three strategies; co-amplification at lower denaturation temperature polymerase chain reaction (COLD-PCR), inverse-PCR and Pippin Prep™ gel electrophoresis, were analysed to identify a novel approach to selectively enrich shorter cffDNA fragments from larger maternal cell-free DNA (cfDNA). The sensitivity of droplet digital PCR (ddPCR) against real-time PCR (qPCR) was compared for fetal sex and RHD genotyping. In addition RHD zygosity testing was carried out for non-maternal samples. Consequently, Pippin Prep™ gel electrophoresis was combined with ddPCR analysis for the NIPD of Down Syndrome (DS) in pseudo-maternal samples. The results revealed that the Pippin Prep™ gel electrophoresis enrichment approach successfully demonstrated 2-fold to 5-fold increases in the cffDNA fraction. However, further optimisation assays of COLD-PCR and inverse-PCR using actual maternal samples were required. The spike experiments for DS detection revealed that with the present assay IV overrepresentation of the chromosome 21 target could be significantly detected for samples with ≥15% ‘cffDNA fraction’. In conjunction with the Pippin Prep™ enrichment method, this would have enabled assessment of all 10 maternal samples. Alternatively, fetal sex and RHD genotyping results determined that ddPCR provides a more sensitive platform compared to qPCR approaches, particularly for samples that express low cffDNA fractions (<2%). The ddPCR platform also proved to be a rapid and accurate system for the determination of RHD zygosity. This study highlights that ddPCR could be used as opposed to qPCR for accurate determination of fetal sex and RHD status. While sequencing approaches currently provide the most sensitive platforms for NIPT of fetal aneuploidy, high costs (>£400) prevent universal application. The combination of cffDNA enrichment with ddPCR analysis could provide a cheaper and more widely available platform for NIPD. However, further large scale validation studies using actual maternal samples are required.

Ce mémoire examine la pratique du dépistage prénatal et du diagnostic prénatal (désormais les tests prénataux ) en deux temps. D’abord, et après une brève mise en contexte, je présente une analyse des facteurs qui ont influencé la mise en place du Programme québécois de dépistage prénatal de la trisomie 21 (PQDPT21). En me basant sur la littérature gouvernementale, je démontre comment un ensemble de pressions politiques, éthiques et sociales a mené à l’impératif d’PQDPT21. Ensuite, je présente une revue de la recherche qualitative à propos de l’expérience de poursuivre une grossesse affectée par l’aneuploïdie fœtale, y compris la trisomie 21. Les principaux résultats de cette revue suggèrent que la ‘rhétorique’ du choix n’est pas toujours démontrée lorsque les parents amènent à terme un fœtus diagnostiqué avec aneuploïdie. Ensuite, je discuterai de l’ensemble de ces travaux selon le concept foucaldien de biopolitique, où les normes et la normalisation agissent sur la régulation politique et sociale. En conclusion, des recommandations pour la recherche et la pratique sont proposées, principalement la nécessité de documenter l’expérience vécue des personnes qui participent aux tests prénataux et d’intégrer ces constatations dans les décisions politiques et dans l’éducation des professionnels de la santé. / This thesis examines the practice of prenatal screening and prenatal diagnosis (henceforth “prenatal testing”) from two angles. Firstly, following a brief introduction to provide context, I present a framework analysis of the factors that influenced the implementation of the Trisomy 21 Prenatal Screening Program of Québec (T21PSPQ). Using governmental literature, I demonstrate how a combination of political, ethical and social pressures led to the imperative of the T21PSPQ. I then present a scoping review of primary empirical qualitative research regarding the experiences of continuing a pregnancy affected by fetal aneuploidy, including trisomy 21. The main findings of this review suggest the ‘rhetoric’ of choice is not always demonstrated in cases where prospective parents bring to term a fetus diagnosed with aneuploidy. The results of this work are then discussed through the Foucauldian concept of biopolitics, where norms and normalization are the principal forms of social and political regulation. Finally, recommendations for research and practice are offered, mainly the need to document the lived experience of those participating in prenatal testing and to incorporate those findings into policy making and into education for health care professionals.