Filter for showing products that fall in between a date

Hi, wonderful community!

I have a subscription company that gives new toys to our customers every month. I’m trying to create a view that shows:

• All the toys in stock
• Toys that have not been given to this customer
• Toys that are appropriate for her child

I’ve managed to do 1 & 2. Any ideas of how I can accomplish the third one?
I have got a field that shows for which Date of Birth this toy is suitable, start and end date.
I know the Date of Birth of the customers child, it needs to be between the start and end of the toy…

Thanks!