The sex of a baby can be determined as early as 6 to 10 weeks into pregnancy depending on the method used.
- The earliest highly accurate method is the Non-Invasive Prenatal Testing (NIPT) blood test, which can determine sex with over 99% accuracy as early as 10 weeks by detecting fetal DNA in the mother's bloodstream.
- At-home gender prediction blood tests claim to provide results from 6 weeks, though these are not always FDA-verified and may have contamination risks.
- Ultrasound can start to predict sex around 11 to 14 weeks using the "nub theory," but accuracy is lower early on (~70% at 11 weeks) and improves to over 95% around 18 to 22 weeks during the anatomy scan, which is the most commonly relied-upon method.
- More invasive tests such as chorionic villus sampling (CVS) at 10 weeks or amniocentesis at 15 to 20 weeks can also provide very accurate sex determination but are mainly used for genetic health screening.
In summary, the soonest reliably accurate method to learn a baby's sex is a blood test like NIPT around 10 weeks, while ultrasound is most accurate between 18-22 weeks. Some at-home tests can give early indications from 6 weeks but should be confirmed later.
