Objective: To explore the clinical significance of trisomy 7 signaled by non-invasive prenatal testing (NIPT).
Methods: Pregnant women with high risk for trisomy 7 by NIPT from January 2017 to December 2023 were selected as the study subjects, and the results of prenatal diagnosis and follow-up were analyzed. Literature related to pregnant women with a high risk for trisomy 7 by NIPT from January 2016 to July 2024 was retrieved from China Biomedical Literature Database, Wanfang Database, China National Knowledge Infrastructure and PubMed database. Relevant information such as the incidence of trisomy 7 by NIPT, positive predictive value (PPV), and pregnancy outcomes were collected. This study has been approved by the Medical Ethics Committee of Lianyungang Maternal and Child Health Care Hospital (Ethics No. JS2022010).
Results: A total of 51 women with a high risk for trisomy 7 by NIPT were identified. Thirty-two of them had chosen chromosomal microarray analysis (CMA) of amniotic fluid cells, and 1 case of mosaic trisomy 7 was detected, which had yielded a PPV of 3.13%. Four women had opted termination of pregnancy, 1 had miscarriage, 4 had pre-term and/or low weight birth, whilst the remaining 42 (82.4%) had full-term delivery. In total 19 literature were retrieved, which had involved 278 cases of trisomy 7 signaled by NIPT, among which 5 fetuses with mosaic trisomy 7 (3.14%) were confirmed. Among the 211 women with follow-up outcomes, 2 (0.95%) had intrauterine growth restriction, 3 (1.42%) had abnormal fetal structure detected by ultrasound, 2 (0.95%) had miscarriage, 9 (4.27%) underwent pregnancy termination, 28 (13.27%) had preterm and/or low weight birth, whilst 167 (79.14%) had normal delivery. In 18 cases, chromosomal analysis of placental tissue was carried out, and 17 were confirmed to have mosaicism trisomy 7.
Conclusion: The PPV for trisomy 7 signaled by NIPT is extremely low. Although most of such women had a full term delivery, adverse pregnancy outcomes may still occur in a minority of cases. Clinicians should provide adequate genetic counseling for such women and recommend appropriate prenatal diagnosis strategies and optimal perinatal management plans.