The impact of preimplantation genetic testing for aneuploidy on prenatal screening

Abstract

Objectives To determine whether preimplantation genetic testing for aneuploidy (PGT-A) is associated with a reduced risk of abnormal conventional prenatal screening results in singleton pregnancies conceived using in vitro fertilization (IVF). Methods This was a retrospective cohort study of singleton IVF pregnancies conceived from a single tertiary care center between January 2014 and September 2019. Exclusion criteria included mosaic embryo transfers, vanishing twin pregnancies, and cycles with missing outcome data. Two cases of prenatally diagnosed aneuploidy that resulted in early voluntary terminations were also excluded. The primary outcome of abnormal first or second-trimester combined screening results was compared between two groups: pregnancy conceived after transfer of a euploid embryo by PGT-A vs. transfer of an untested embryo. Multivariable backwards-stepwise logistic regression with Firth method was used to adjust for potential confounders. Results Of the 419 pregnancies included, 208 (49.6%) were conceived after transfer of a euploid embryo by PGT-A, and 211 (50.4%) were conceived after transfer of an untested embryo. PGT-A was not associated with a lower likelihood of abnormal first-trimester (adjusted OR 1.64, 95% CI 0.82–3.39) or second-trimester screening results (adjusted OR 0.96, 95% CI 0.56–1.64). The incidences of cell-free DNA testing, fetal sonographic abnormalities, genetic counseling, and invasive prenatal diagnostic testing were similar between the two groups. Conclusions Our data suggest that PGT-A is not associated with a change in the likelihood of abnormal prenatal screening results or utilization of invasive prenatal diagnostic testing. Counseling this patient population regarding the importance of prenatal screening and prenatal diagnostic testing, where appropriate, remains essential.

Challenges experienced by genetic counselors while they provided counseling about mosaic embryos

“…At this time, the short- and long-term health outcomes of children born from mosaic embryos involving different chromosomes, types of mosaicism (segmental vs. whole chromosomes), and levels of mosaicism (% aneuploid) are unknown ( 14 , 15 , 16 ). Additionally, prior literature suggests that uptake of diagnostic testing among pregnancies conceived with euploid embryos or untested embryos (no PGT-A used) is low ( 17 , 18 ). It is also uncommon for apparently healthy newborns to undergo postnatal testing ( 4 ).…”