Early fetal sex determination has become more prevalent among parents interested in planning for their unborn child. Current advances in non-invasive prenatal testing (NIPT) have facilitated this desire with safe and efficient methods such as the SneakPeek® Early Gender DNA Test (“SneakPeek”). Here, we report the accuracy of SneakPeek® from a large-scale clinical study of 1,029 pregnant women between 7 and 37 weeks of gestation (median =10 weeks). A follow-up survey was conducted on all study participants to determine whether the birth sex of their child matched the fetal sex test result reported by SneakPeek®. Venipuncture blood samples were collected from pregnant women in October through December of 2019, and subsequently analyzed with SneakPeek® to determine fetal sex. After birth, a survey was conducted to obtain live birth information for all participants in the study. Y-chromosome DNA was detected in 505 of the 506 samples from mothers that gave birth to baby boys, providing 99.8% sensitivity. Gender of all 523 newborn girls was identified correctly, resulting in 100% specificity. There were no cases of male DNA contamination identified in this study (i.e. no false positives). In the largest qPCR-based fetal sex test study to date, SneakPeek® test results were confirmed using the gold standard of the baby’s sex at birth. With 99.9% accuracy, SneakPeek® is the most reliable early fetal sex text available for expectant parents