Same thing happened to us only we were told we were having our second son. Indeed my own daughter (yes, the one who was also the 'blighted ovum') was determined to be our son at our second trimester ultrasound.
My husband and I already had a son and decided we just wanted to be surprised at the next birth. We told the doctor this a number of times and the ultrasound tech. This was our longer second-trimester ultrasound. She took all sorts of measurements but made sure not to refer to the baby's gender. After awhile, another ultrasound tech came in to take her place. They spoke for awhile. As the new tech took over scanning, I was just getting ready to make sure she knew we didn't want to know the gender when she announced excitedly that it was a boy. Sigh...she saw our disappointment. Not because the baby was a boy but because we had wanted to be surprised. She apologized profusely. Toward the end of the ultrasound, she said let me take one more look. She took a couple minutes and told us "Not to count our chickens before they were hatched," but she'd already announced our 'son' and this was to be our last ultrasound.
And, so we prepared for our baby boy. Thankfully, I still had a lot from my son so I didn't spend too much. I did buy a new stroller and carseat, both in light green. I also bought a bouncy seat in blue but that was about it.
So, my water broke and long crazy story short but we get my husband home from another state before they take me in for my C-section. With my husband standing there holding my hand, they pull out our baby and announce, "It's a girl!"
Whoa, total shock! I had two doctors in there and I remember I just kept asking, "Are you sure he's a girl?" They'd laugh and assure me *she* was a girl. Hubby even assured me the baby was a girl but he just looked like he was in shock so I didn't put too much stock in his assessment. Finally, they had her cleaned up and brought her over. Yep, noticeable lack of body parts. She was a girl!
So amazing! It took me a month or so of changing diapers before it really sunk in I think. I had just gone about four or five months believing she was a boy.
And, that girl is all girl. She's my dancer and my musician. She loves life to the fullest and she has made our world a brighter place.
So, yes, even gender can be 'misdiagnosed' during pregnancy :)
My Baby Girl