Hypothesis: human trophectoderm biopsy downregulates the expression of the placental growth factor gene

Maternal Placental Growth Factor (PlGF) levels, sonographic placental parameters, and outcomes of IVF pregnancies with and without embryo trophectoderm biopsy

PURPOSE

In vitro fertilization (IVF) is associated with abnormal trophoblast invasion and resultant decreased levels of circulating placental biomarkers such as placental growth factor (PlGF). Our objective was to evaluate maternal serum levels of second/third trimester PlGF, sonographic placental parameters, and clinical outcomes among IVF frozen embryo transfer (FET) pregnancies with and without embryo trophectoderm biopsy.

METHODS

This was a retrospective study of pregnant patients who conceived using a single frozen embryo transfer (FET) and gave birth between 30 January 2018 and 31 May 2021. We compared PlGF levels, sonographic placental parameters, and clinical outcomes between FET with biopsy and FET without biopsy groups.

RESULTS

The median PlGF level was 614.5 pg/mL (IQR 406-1020) for FET pregnancies with biopsy, and 717.0 pg/mL (IQR 552-1215) for FET pregnancies without biopsy. The adjusted mean difference was 190.9 pg/mL lower in the FET biopsy group (95% CI, -410.6, 28.8; p = 0.088). There were no statistically significant differences in placental parameters or clinical pregnancy outcomes.

CONCLUSION

This exploratory study demonstrated a possible trend toward lower maternal serum PlGF in the pregnancies conceived with FET using a biopsied embryo. Further investigation is warranted into the potential placental health effects of trophectoderm biopsy.

Impact of trophectoderm biopsy for preimplantation genetic testing on obstetric and neonatal outcomes: a meta-analysis

OBJECTIVE

This study aimed to investigate whether trophectoderm biopsy for preimplantation genetic testing is associated with an increased risk of adverse obstetrical and neonatal outcomes compared with conventional in vitro fertilization or intracytoplasmic sperm injection without preimplantation genetic testing.

DATA SOURCES

Entries between January 1990 and August 2022 were searched using MEDLINE, Embase, Web of Science, the Cochrane Library, and Google Scholar.

STUDY ELIGIBILITY CRITERIA

Publications comparing the outcomes of pregnancies after preimplantation genetic testing using trophectoderm biopsy and in vitro fertilization or intracytoplasmic sperm injection were included. Only human studies with a cohort or case-control design or randomized controlled trials were eligible for inclusion.

METHODS

The study selection process was performed independently by 2 investigators. The quality of the observational studies was assessed using the Newcastle-Ottawa Scale, and the Cochrane risk-of-bias tool version 2 was used to grade the level of bias in randomized controlled trials. The pooled odds ratio and 95% confidence interval were calculated using a random-effects model when substantial heterogeneity occurred (indicated by I2 of >50% and P<.1). Otherwise, a fixed-effects model was used.

RESULTS

This meta-analysis included 13 studies involving 11,469 live births after preimplantation genetic testing treatment with trophectoderm biopsy before embryo transfer and 20,438 live births after in vitro fertilization or intracytoplasmic sperm injection only. The odds ratio of preterm delivery was higher in the trophectoderm-biopsied group than in the routine in vitro fertilization or intracytoplasmic sperm injection group (pooled odds ratio, 1.12; 95% confidence interval, 1.03-1.21); however, the difference did not exist after sensitivity analysis (odds ratio, 0.97; 95% confidence interval, 0.84-1.11). The risk of low birthweight did not increase among the biopsied pregnancies (pooled odds ratio, 1.01; 95% confidence interval, 0.85-1.20). No marked difference was observed in the risk of other obstetrical or neonatal outcomes between the biopsy and control groups. Furthermore, no difference was noted in the perinatal outcomes between trophectoderm-biopsied and nonbiopsied groups in the subgroup analyses by intracytoplasmic sperm injection, frozen-thawed transfer, or single embryo transfer.

CONCLUSION

Trophectoderm biopsy for preimplantation genetic testing treatment did not alter the risk of obstetrical or neonatal outcomes compared with conventional in vitro fertilization or intracytoplasmic sperm injection without preimplantation genetic testing. However, this study was limited by the large observational evidence base, and more randomized controlled trials are needed to further confirm these findings.

Comment on the recent PGDIS Position Statement on the Transfer of Mosaic Embryos 2021

The worldwide demand of preimplantation genetic testing for aneuploidy (PGT-A) is still growing. However, chromosomal mosaic results greatly challenge the clinical practice. The recently published PGDIS Position Statement on the Transfer of Mosaic Embryos is the third PGDIS position statement on how to deal with embryos diagnosed as chromosomal mosaics (CM) and, one of many attempts of different societies and working groups to provide a guideline for clinicians, laboratories, clinics, and genetic counselors. But still, as in previous statements, many issues remained unresolved. Moreover, from our point of view, the question how to deal with embryos diagnosed as CM, consisting of two or more karyological cell lines cannot be separated from all the other aspects of PGT-A including its accuracy. The paucity of clearcut indications for PGT-A and evidence of benefit as well as an overall cost-benefit assessment is given below.