Ultrasound may be a key tool for doctors to determine the health of a fetus, but for many expectant parents, it's key for another important (and exciting) reason: It can clue you in on whether you're expecting a boy or girl! But when it comes to figuring out your baby's sex, how accurate are ultrasounds, really?
Pretty darn accurate, as it turns out: One recent study found that 98 percent of the time, the ultrasound tech correctly predicted the gender of the baby. Still, the accuracy of your individual ultrasound will depend on a number of factors, including:
Early ultrasounds may not be the best, most accurate gauge of whether you're expecting a boy or girl, according to some experts. "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 Michele Hakakha, M.D., a Beverly Hills-based ob-gyn and the author of Expecting 411. "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. "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. Bottom line: Don't go out and buy that pretty pink dress after your first ultrasound -- unless you keep the receipt!
If your little one doesn't cooperate during your ultrasound, you may not get that boy or girl determination until he or she arrives. "Some fetuses are bashful and keep their legs together and impair determination of the gender," says Dr. Putterman. "If they are not clearly visualized, mistakes can be made when sonographers guess the gender based on a suboptimal examination." If your sonographer is having a tough time seeing between your baby's legs, take any answer you get from her with a grain of salt.
If you're carrying twins or triplets (or more!), your babies could hide their siblings, making determination of the sex of each baby more difficult.
If you're plus-size, that additional body mass 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," Dr. Hakakha says.
In general, you can take your sonographer's word for it if she says boy or girl -- but be prepared with another name, just in case!
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