UBC Theses and Dissertations
Birth outcomes, placental metrics, and imprinted genes in pregnancies conceived via assisted reproductive technologies Schafer, Samuel J.
Infertility, the inability to achieve a natural pregnancy within twelve months, affects roughly 10% of couples worldwide. To address this difficulty, many people use assisted reproductive technologies (ART) such as in vitro fertilization, intracytoplasmic sperm injection, and intrauterine insemination. There is some concern over the safety of these techniques, however, as some adverse birth outcomes such as growth restriction, low fetoplacental weight ratio, and preterm birth, as well as certain developmental disorders known as imprinting disorders have been reported at higher rates in children conceived via ART. In this thesis, I investigate a number of birth outcomes and placental metrics as they relate to different factors of ART procedures. I also evaluate expression levels and DNA methylation (DNAme) profiles of imprinted genes in the context of births that display some of the adverse outcomes associated with ART. Birth weight, gestational age at birth, and APGAR scores at one and five minutes were not seen to be significantly different between ART and spontaneously conceived (SC) children. Placental metrics (weight, diameter, thickness), however, were seen to be significantly larger in ART children. These differences were most closely associated with which ART technique was used and whether or not it included in vitro embryo culturing. DNAme and expression profiles of imprinted genes associated with imprinting disorders did not differ significantly between births with low and normal fetoplacental weight ratios, despite previous studies finding significant differences between ART and SC in the same dataset. When only considering births that were preterm, growth-restricted, or of abnormal birth weight for their gestational age, expression of imprinted genes was not seen to be significantly different between ART and SC. The findings of these studies suggest that an increase in placental size is rather consistent among ART births, while the altered expression and DNAme profiles sometimes reported for ART are less common and more stochastic. There is also some evidence to suggest that the increased placental size is largely attributable to the in vitro culturing and ART techniques themselves, while the changes in DNAme and gene expression sometimes seen may be more attributable to the underlying infertility.
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