The gender of a baby can typically be found out during the anatomy scan ultrasound, which is usually performed around 18 to 22 weeks of pregnancy, with 20 weeks being the most common time for this scan. This scan can reveal the baby's gender if the baby is positioned well and the technician is experienced. Alternatively, the baby's gender can sometimes be found earlier through non-invasive prenatal testing (NIPT), a blood test done from about 10 weeks of pregnancy, which looks at the baby's DNA in the mother's blood. Some early ultrasound methods like the "nub theory" can estimate gender as early as 11 to 13 weeks, but accuracy increases with the progression of the pregnancy. In summary:

• Most common and reliable method: ultrasound anatomy scan around 18-22 weeks
• Earliest genetic blood test (NIPT): from around 10 weeks
• Early ultrasound gender prediction: possible from 11 weeks but less certain until 18-22 weeks

Therefore, parents often find out the baby's gender around the 20-week ultrasound scan or potentially earlier with advanced testing methods if desired.