First- and Second-Trimester Aneuploidy Screening Biomarkers and Risk Assessment of Placenta Previa and Accreta: A Systematic Review and Meta-Analysis

Objective

This study evaluates differences in first and second-trimester maternal serum biomarkers for aneuploidy screening among women with placenta accreta spectrum (PAS) disorders, placenta previa, and those with normal placentation.

Data Sources

A systematic review of 5 major databases up to April 2023 was conducted. Included were comparative studies analyzing mean biomarker levels in multiples of the median (MoM) among pregnant women with PAS, placenta previa, and uncomplicated pregnancies.

Study Selection

Both observational studies and randomized controlled trials were included in this meta-analysis.

Data Extraction and Data Synthesis

Analysis of 8 retrospective studies involving 1886 participants showed significant variances in biomarker levels. In the first trimester, pregnancy-associated plasma protein-A levels were notably higher in the PAS group compared to the placenta previa group (731 patients, mean difference (MD) 0.48 MoM; 95% CI 0.23 to 0.73, P = 0.0001). Also, β-human chorionic gonadotropin levels were elevated in the placenta previa group compared to those with normal attachment (362 patients, MD 0.27 MoM; 95% CI 0.17 to 0.38, P < 0.00001). In the second trimester, alpha fetoprotein and human chorionic gonadotropin levels were significantly increased in PAS patients compared to the placenta previa and normal groups, indicating potential markers for PAS.

Conclusions

Significant differences in early pregnancy biomarker levels among women with PAS, placenta previa, and normal placentation were identified. These findings suggest potential for early screening, but further large-scale studies are essential for validation. This study underscores the need for improved screening methods for placental disorders, potentially aiding in early diagnosis and management strategies.