I am in week 19 of my pregnancy and when they did an ultrasound a couple of days ago they said that I am having a girl. Could they be wrong at this point in my pregnancy?”
Yes, gender predictions made by looking at an ultrasound are sometimes wrong. The chances of a mistaken gender call are higher if the ultrasound machine was one of the older ones with a fuzzy picture, if the baby was moving around a lot or in a position that made it difficult for the technician to see, or if the technician was inexperienced or just couldn’t get a clear picture for whatever reason. What the technician is looking for is a penis and scrotum, which will look kind of like a triangle, (and is sometimes called the “turtle sign” or the “triangle sign,”) or a labia, which looks like a stripe of two or three lines (sometimes called the “hamburger sign” as the labia side-by-side look kind of like a hamburger bun). At 19 weeks what they’re trying to see is only about a centimeter long, so the difference between the signs aren’t always as obvious as they might sound.
Some technicians have also been known to go by the “if there’s not a penis it’s a girl” rule, and that can be misleading. It can help to ask the technician to show you exactly what it is s/he’s looking at. Caveats aside, if you went to a radiology lab that had a fairly modern ultrasound machine, with a 3-D “golden” digital image instead of a flat black-and white one, and the technician seemed confident that he or she had a clear view, then a mistake is a lot less likely. Many technicians will give you a printout of the image– if you have a printout, you may want to go online (About.com has a gallery) and compare the images of “turtles” and “hamburgers” to see which one your image looks most like.