Gender Ultrasound: Are You Having a Boy or Girl?
Ultrasounds are a key tool for analyzing the health of your fetus, but they can also serve another exciting purpose: Revealing whether you're having a boy or girl. But how do gender ultrasounds work, and are they always accurate? We spoke with experts to break down your most pressing questions.
How Do Gender Ultrasounds Work?
Some people choose to wait until their baby is born to find out if they're having a boy or a girl. Others want to know as soon as possible. Ultrasounds are a non-invasive way to find out.
However, rather than gender, which is a personal identity, what ultrasounds really reveal is the likely biological sex of your baby. Also, note that a person's gender may change later in life and be different from the biological sex they are assigned at born. That said, studies show that an ultrasound between the 11th and 12th week of gestation is approximately 75% to 91% accurate in determining fetal sex.
So, while fairly accurate, the tests are not definitive. The variation in accuracy is based on factors like the skill of the technician, the quality of the ultrasound machine, timing, and the body placement of the fetus. (More on test accuracy below.)
What happens during the exam
While you're reclining on an exam table, the ultrasound technician will slather gel on your belly. Then, they'll glide over it with a plastic transducer that emits high-frequency sound waves. These waves bounce off of your little one's body to produce an image of their soft tissues, organs, and other anatomical structures—including reproductive parts. The image will be displayed on a monitor for you (and anyone you may have with you) to see.
When done by a trained technician for medical purposes, ultrasounds are considered safe, and they don't involve X-rays or radiation. The exam also doesn't hurt at all, although the gel may feel cold and be a bit messy.
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Accuracy of Boy vs. Girl Ultrasound Predictions
As it turns out, ultrasounds are pretty accurate at determining the sex of your baby, particularly in the 2nd and 3rd trimesters. Studies have found that ultrasound technicians correctly predict a baby's sex nearly 100% of the time after the first trimester. Still, the accuracy of the results of your individual exam will depend on a number of factors, including timing, your baby's position, your body size, and whether you're carrying multiples.
Timing
How far along the pregnancy is makes a big difference. "The accuracy of the ultrasounds increases as gestational age advances," says Bart Putterman, M.D., an OB-GYN at Texas Children's Pavilion for Women in Houston. Waiting until the second trimester increases the likelihood of getting an accurate reading because the fetus's sexual organs are more developed—and easier to see.
Your Baby's Position
If your sonographer is having a tough time seeing between your baby's legs, this will impair their ability to determine your baby's sex. "Some fetuses are bashful and keep their legs together and impair determination of gender," says Dr. Putterman. "If they are not clearly visualized, mistakes can be made when sonographers guess the gender based on a suboptimal examination."
Your Body Size
If you're plus-sized, additional body size can prohibit a clear image of your baby. "Determining a fetus' sex on ultrasound is certainly more difficult in women who are overweight or obese," says Michele Hakakha, M.D., a Beverly Hills-based OB-GYN and the author of Expecting 411. However, an experienced ultrasound operator can usually work around this complication.
Pregnancy with Multiples
If you're carrying twins or triplets (or more!), your babies could hide their siblings, making a determination of the sex of one or more of the babies more difficult.
When Should I Get a Gender Ultrasound?
As noted above, early ultrasounds aren't the most accurate gauge of whether you're expecting a boy or girl. "The earliest in pregnancy that the fetus's sex can be determined by ultrasound is about 12 weeks, and even then, it can be very difficult," says Dr. Hakakha. "The external genitalia—the vulva or penis and scrotum—are not actually external until about 13 weeks."
You may want to wait until your later ultrasounds, such as your 20-week anatomy scan, for a more definitive answer. Bottom line: Don't go out and buy that pretty newborn dress after your very first ultrasound, unless you keep the receipt!
