How many months into pregnancy can you tell the gender of your baby? How many months into your pregnancy can you tell the gender of your baby? This is a question that many expectant mothers are concerned about. Generally speaking, the gender of the fetus can only be determined through B-ultrasound around 18-20 weeks, but this also depends on factors such as the size and posture of the fetus. Before that, some methods can help you initially predict the gender of the fetus. The most popular method for determining fetal gender