The sex of a baby can be determined as early as about 6 weeks through at-home early gender DNA blood tests, which have over 99% accuracy. Medically, non- invasive prenatal tests (NIPT) and chorionic villus sampling can determine the baby's sex starting around 10 weeks. Ultrasound methods generally allow gender determination between 11 and 20 weeks, with the most common anatomy scan taking place between 18 to 22 weeks, where sex can be seen more clearly and accurately. The earliest ultrasound method, using the "nub theory," can predict sex at 11 weeks but with lower accuracy (about 70.3%) which improves with time advancing in pregnancy. The most reliable results typically come from blood tests or invasive genetic tests early in pregnancy, or from ultrasound scans during the second trimester.
Early Blood Tests
- At-home blood tests like the SneakPeek test can identify sex as early as 6 weeks with over 99% accuracy.
- Non-invasive prenatal testing (NIPT) is performed around 10 weeks, analyzing fetal DNA in the mother's blood.
Ultrasound
- Earliest ultrasound detection by the "nub theory" can be done at about 11 weeks with moderate accuracy (~70%).
- Routine anatomy ultrasound scans between 18-22 weeks usually provide a clearer and more accurate determination of sex.
Genetic and Invasive Tests
- Chorionic villus sampling (CVS) at about 10 weeks and amniocentesis between 15-20 weeks can confirm fetal sex with high accuracy by analyzing chromosomes.
Overall, while sex can be detected very early with advanced DNA blood tests and genetic methods, most parents find out around 18-22 weeks via ultrasound scan.
