In a pregnancy ultrasound, the term "gender XY" refers to the presence of a male fetus. The chromosomes responsible for determining gender are X and Y, with males having one X and one Y chromosome. When an ultrasound indicates gender XY, it means that the fetus has a Y chromosome, indicating that it is biologically male. This information can be important for parents who are curious about their baby's gender or for medical professionals monitoring fetal development. It is essential to note that while ultrasound can provide insights into fetal gender, it is not always 100% accurate and should not be solely relied upon for making definitive conclusions about a baby's gender.