The impact of preimplantation genetic testing for aneuploidy on prenatal screening

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.

Determinant of Prenatal Diagnostic Testing Among Women with Increased Risk of Fetal Aneuploidy and Genetic Disorders.

Objective: This study aimed to assess factors that influence patients’ decisions in accepting prenatal diagnostic testing following genetic counseling for increased risk of fetal aneuploidy. Methods: A retrospective cohort study of women at increased risk of fetal aneuploidy who had genetic counseling from January 2012 to December 2016 at a single academic center. Demographics, indications for genetic counseling and rates of diagnostic testing were collected and compared between those who accepted diagnostic testing and those who chose cell free DNA. The variables were analyzed using chi-square, Fisher exact test, and multiple logistic regression. Result: Of the 2373 pregnant women who underwent genetic counseling for increased risk of fetal aneuploidy during the study period, 321 women had diagnostic testing (13.5%). Women at 35 years and older accepted diagnostic testing more than women younger than 35 years (20.7% versus 11.5%, p < 0.001). Asian women accepted diagnostic testing at 27.7% more than white, non-Hispanic Black and Hispanic women at 18.0%, 12.1% and 11.7% respectively, p = 0.002. Number of indications for genetic counseling influenced the likelihood of accepting diagnostic testing. Women with one indication had 11.5% acceptance of diagnostic testing; and with two and three indications, it was 17.0% and 29.2% respectively. The commonest indication for diagnostic testing was cystic hygroma (RR 7.5, 95% CI 3.12-8.76 p < 0.001). The relative risk of diagnostic testing for fetuses with shortened long bones; femur and humerus, thickened nuchal fold, echogenic bowel, single umbilical artery, increased nuchal translucency were 4.0, 3.3, 3.1, 2.7, and 2.7 respectively. Abnormal serum analyte alone was associated with less acceptance of diagnostic testing (RR 0.8, 95% CI 0.7 – 0.96, p = 0.017). Conclusion: Age, race, ethnicity and cumulative number of indications for genetic counseling influenced acceptance of diagnostic testing in at-risk women of fetal aneuploidy and genetic disorders