Snippy childrens python!! plausible reasons for this?

It's fairly common for baby children's to be a bit snappy, you're just a big predator to them. They'll grow out of it, just keep handling him regularly and he'll calm down. Not sure if you already do this, but when you're picking him up try not to come from above, go from the side of him and scoop him up, should help a bit. Once picked up they start to realise that they're not going to be eaten! I really doubt it has anything to do with you being pregnant/the rain. My spotted python is about a year old and he's as soppy as anything, so yours will be like that eventually.