Frequency of unnecessary prenatal diagnosis of hemoglobinopathies: A large retrospective analysis and implication to improvement of the control program

OBJECTIVE: To determine the frequency and etiology of unnecessary prenatal diagnosis for hemoglobinopathies during 12 years of services at a single university center in Thailand. METHODS: We conducted a retrospective cohort analysis of prenatal diagnosis during 2009–2021. A total of 4,932 couples at risk and 4,946 fetal specimens, including fetal blood (5.6%), amniotic fluid (92.3%), and chorionic villus samples (2.2%) were analyzed. Identification of mutations causing hemoglobinopathies was carried out by PCR-based methods. Maternal contamination was monitored by analysis of the D1S80 VNTR locus. RESULTS: Among 4,946 fetal specimens, 12 were excluded because of poor PCR amplification, maternal contamination, non-paternity, and inconsistency of the results of the fetuses and parents. Breakdown of 4,934 fetuses revealed 3,880 (78.6%) at risk for the three severe thalassemia diseases, including β-thalassemia major, Hb E-β-thalassemia, and homozygous α(0)-thalassemia, 58 (1.2%) at risk for other α-thalassemia diseases, 168 (3.4%) at risk for β(+)-thalassemia, 109 (2.2%) at risk for high Hb F determinants, 16 (0.3%) at risk for abnormal Hbs, and 294 (6.0%) with no risk of having severe hemoglobinopathies. The parents of 409 (8.3%) fetuses had inadequate data for fetal risk assessment. Overall, we encountered unnecessary prenatal diagnostic requests for 645 (13.1%) fetuses. CONCLUSIONS: The frequency of unnecessary prenatal diagnosis was high. This could lead to unnecessary risk of complications associated with fetal specimen collection, psychological impacts to the pregnant women and their families, as well as laboratory expenses and workload.