I think you need to consider if you're 'hoping' for one sex. Gender disappointment is a common thing and if you're hoping to have a girl after 2 boys and wait for your 'surprise' you may find yourself upset at first if you have a boy OR you could be unbelievably happy either way .

I didn't wait for a surprise either but that was my first and under different circumstances. But I just couldn't wait LOL!!! All the best and let us know what decision you go with!!