Um, can I just point out that you and you wife aren’t definitely actually having anything, you might be though (it’s why it’s generally not a good idea to find out the sex in advance). The bodies QA/QC process is very rigorous indeed.
For similar reasons it’s a little premature to choose a name before the big day.
But Elsa was nicknamed Beans even before she was born as there wasn’t a single moment in the 9 months my wife carried her that she wasn’t trampolining or something in mum’s tummy. Hence Jumping Beans, full of Beans, baby Beans, she was and always will be Beans.
Hence Polly also became Polly Peas, and the two together are Peas and Beans.