Mother in law wants to go to the gender scan reveal

I'm not sure where to post this, but I just got asked by my Mother in law If she can come to the scan when my SO and I find out the gender of our baby, I sort of feel awkward and uncomfortable with her coming along because I want it to just be me and my SO. I did say to her that when we find out, we'll do a little family gathering and that we'll find out all together, she wasn't so keen on this. I just feel like that once she knows, she's going to tell everyone the gender and ruin the surprise. Am I being too selfish or should I let her come along?