how far along do you have to be to know the gender of a baby

The gender of a baby can typically be determined with reasonable accuracy starting around 14 to 16 weeks of pregnancy using ultrasound. The most common and reliable time for ultrasound gender determination is at the anatomy scan, usually done between 18 and 22 weeks. Noninvasive prenatal testing (NIPT) can also reveal the baby's genetic sex from around 10 weeks of pregnancy with high accuracy, but it is primarily used for screening chromosomal abnormalities. Earlier ultrasound methods like the "nub theory" around 11 to 13 weeks can provide clues, but they are less reliable than scans performed later.