I have a friend who just found out the gender of her baby changed literally 3 weeks before she was due. She was told she was having a boy, bought everything boy! Went in for her last scan 3 weeks before her due date to find out she's having a girl! Luckily my ob was right. Got checked twice by two doctors (having a girl)
my dr's office told me to keep my receipt after they tell me the gender, so apparently my hospital is not very good at reading them. we have everything already bought and it's all neutral. i have couple girl outfits and a couple boy outfits as well. we will be happy with either and have our names picked out.
I know a girl that's due a couple weeks before me, she was told she was having a girl at her 20 week scan, and a month later they did another scan and found it was actually a boy! I feel like it doesn't happen often though