When my mom was pregnant with my oldest brother, she was certain he was a girl. This was in the early 1980s before a sonogram could tell you the sex of your baby.
But my mom says she just knew he was a girl. She was so sure, she and my dad named him Isabelle and called him that while he was still in the womb.
Imagine their surprise when he popped out and was definitely not an Isabelle.
Stuff like this happened all the time before the 1980s when it became pretty common to get a sonogram that could tell you the sex of your baby.
But these days, most people aren't usually surprised by the sex of their newborn. Sonograms can tell you what sex your baby will be as early as 18 weeks into pregnancy. There are even sonograms that can give you a 3D image of your baby while it's growing inside you if you're really desperate to get a peak. (Although personally, I think the 3D sonograms make all babies look like squished aliens and they scare me, but that's something I can work out in therapy).