no one month has the most.
april and december have 2 each (2 nieces in april and then my sister and her DH in december)
then there's one niece in january, me in may, my nephew in june, my mom in july, my dad in august, and my other sister in november.
it does seem like i never stop spending money on presents between november and january though since there's 4 birthdays between november 9th and january 9th plus christmas in there.