Efficacy, pregnancy and birth outcomes following IVF treatments in different age groups and with different time for embryo transfer and freezing in Australia and New Zealand, 2002–2008

Abstract

Background: The successful or adverse outcomes of assisted reproductive technology (ART) treatment are primarily determined by woman&#146;s age and number of embryos transferred. However, it is not clear how each additional year of woman&#146;s age impacts the ART treatment outcomes. Inconsistent findings about the relationship between ART treatment outcomes and number of embryos transferred and stage of embryo development still exist in the literature. Differences in the findings relate to what outcome is chosen and how it is measured. The objective of this PhD thesis is to inform infertile patients, fertility professionals and the general population regarding fertility awareness, the optimal goal of an ART treatment and the best population-based clinical practice model. It aims to investigate the age-specific live delivery rate by single year increments, to compare perinatal outcomes of babies following single embryo transfer (SET) with double embryo transfer (DET), to propose a new indicator &#147;healthy baby&#148; as the optimal goal for an ART treatment, and to build a clinical practice model that maximises the likelihood of a &#147;healthy baby&#148;. Materials and methods: The thesis includes five coherent studies using population data extracted from the Australian and New Zealand Assisted Reproduction Database. Pregnancy, live delivery, and &#147;healthy baby&#148; (term liveborn singleton of normal birthweight without congenital anomaly) were used to measure the success of an ART treatment. Results: For patients aged &#8805;35 years, the likelihood of pregnancy and live delivery decreased by each additional year of age. It is appropriate for women aged <43 years to initiate a fresh ART treatment. Singletons following SET had lower odds of adverse perinatal outcomes than those following DET. For fresh cycles in patients aged <35 years, selective transfer of a single blastocyst resulted in a higher rate of &#147;healthy baby&#148; than the transfer of a single cleavage embryo. For thaw cycles, a higher likelihood of a &#147;healthy baby&#148; following transfer of a single blastocyst cultured from thawed cleavage embryos was observed. Transfers of fresh blastocysts and blastocysts cultured from thawed cleavage embryos reduced the risk of miscarriage. Conclusions: This PhD thesis suggests that, from a population perspective, to minimise adverse outcomes in parallel with maximising births of a &#147;healthy baby&#148;, the optimum clinical practice model for younger patients is the selective transfer of a single blastocyst in a fresh cycle and a single blastocyst cultured from thawed cleavage embryos in subsequent thaw cycles. It confirmed the importance of community-based education regarding fertility potential and the benefits of early fertility assessment and ART treatment where clinically indicated. It provided evidence that the continuing increase in SET would improve the overall birth outcomes of ART treatment