Identification of either female or male genitalia on an ultrasound determines the gender of an unborn baby, reports About.com. The Ramzi’s method also uses ultrasound to determine a baby’s gender based on the location of the placenta.
An ultrasound of a baby girl displays female genitalia, including the clitoris and labia, explains About.com. The term “hamburger sign” often describes these features when observed on the ultrasound because the labial lips look like the shape of a bun with the clitoris located in between.
A penis and testicles appear on an ultrasound of a baby boy, according to About.com. Additionally, an erect penis is even more clearly defined on a boy’s ultrasound. The term “turtle sign” frequently describes the appearance of a penis positioned between testicles.
Traditionally, a doctor orders an ultrasound in the middle of a pregnancy to determine a baby’s gender; however, technicians can perform the Ramzi’s method of using ultrasound to determine a baby’s gender at six weeks gestation, reports About.com. With this method, the left side of the uterus shows 97.5 percent of the placenta or chorionic villi of a female fetus, whereas the right side of the uterus displays 97.2 percent of the placenta of a male fetus.