# Prenatal screening of Down syndrome in assisted reproductive techniques pregnancies: A systematic review

## TL;DR

This review examines how prenatal screening for Down syndrome differs in pregnancies from assisted reproductive techniques, highlighting the need for adjusted marker interpretation.

## Contribution

The study systematically reviews how serum and sonographic markers differ in ART pregnancies, suggesting adjusted screening thresholds for accurate Down syndrome diagnosis.

## Key findings

- Pregnancy-associated plasma protein-A is significantly lower in ART pregnancies compared to spontaneous ones.
- Free beta-human chorionic gonadotropin levels are elevated in IVF and ICSI pregnancies.
- Nuchal translucency and some biochemical markers differ in ART pregnancies, affecting screening accuracy.

## Abstract

The interpretation of Down syndrome screening results in assisted reproductive technology (ART) pregnancies is challenging. Despite the high psychological burden that false positive results impose on parents, studies that have addressed interpretation of both serum and sonographic markers in both rounds of screening for Down syndrome diagnosis in post-ART pregnancies are limited.

This review study investigated the types of serum screening and imaging for prenatal diagnosis of Down syndrome in ART pregnancies to know and correctly interpret the results of prenatal screenings in these pregnancies.

In this systematic review, an extensive search was conducted in Persian and English in PubMed, Web of Science, Scopus, SID, and Google Scholar without any time limit until January 2024 using appropriate keywords. PRISMA guideline, STROBE, and CONSORT checklists were used.

Review of 30 articles showed in the first screening, pregnancy-associated plasma protein-A was significantly lower than normal values compared to spontaneous pregnancies, while free beta-human chorionic gonadotropin, especially in the in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) was significantly higher. Some studies also indicated an increase in nuchal translucency in the first trimester of pregnancies resulting from ART. Biochemical markers of second screening, in some studies, showed an increase in inhibin-A, a decrease in α-fetoprotein, and unconjugated estriol were evident compared to normal values.

Marker levels may be different for the presence of ovulation-stimulating hormones, multiple corpora lutea, twins or multiplets, type of IVF, and changes in egg cytoplasm in ICSI. Study suggests concentration of maternal serum markers, especially free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A, should be adjusted differently for each ART (IVF and ICSI separately).