A risk prediction model for fetal hypospadias by testing maternal serum AFP and free beta-HCG

Objective: We aimed to determine the correlation between serum alpha-fetoprotein (AFP), the free human chorionic gonadotropin beta subunit (free beta-HCG) in pregnant women during the mid-trimester, and fetal hypospadias, and tried to establish a risk prediction model. Methods: A multi-center case-control study was conducted. We divided the fetuses into two groups (69 with fetal hypospadias and 62 without fetal hypospadias). Time-resolved immunofluorescence was used to determine the serum levels of AFP and free beta-HCG. The best cut-value and area under curve (AUC) were determined based on the Receiver operating characteristics (ROC) curve, and the diagnostic value of AFP and free beta-HCG was evaluated. Results: The level of AFP in the study group was 1.14 multiple of Median(MOM), which was higher than in the control group (0.96 MOM); the difference was significant (Z = 2.831, P = .005). Similarly, the free beta-HCG level was 1.30 MOM in the study group, and was also significantly higher than in the control group (0.84 MOM; Z = 3.131, P = .004). We used the AFP and free beta-HCG levels separately to predict fetuses with hypospadias, and the AUCs were 0.644 (95% Confidence interval (CI): 0.5500.737, P = .005) and 0.659 (95% CI: 0.5650.752, P = .002), respectively. According to the ROC curve, the best cut-off values for AFP and free beta-HCG were 0.945 MOM and 1.275 MOM, respectively. When we combined the AFP level with the free beta-HCG level, the AUC was 0.700 (95% CI: 0.610-0.789, P < .001), with a sensitivity of 0.551 and a specificity of 0.855. Conclusion: Combined screening for fetal hypospadias with maternal serum AFP and free beta-HCG levels during the early second trimester has high sensitivity and specificity, which can be used as a new marker.