Just something I was thinking about last night, DS was born May 30th. So in February he will be 9 months, but there's no 30th day in that month, so what day would you consider him to be 9 months? Oh, the things I think about in the middle of the night...
Re: if LO was born on the 30th or 31st...
I agree. The last day of the month.
What PPs have said. February is just one of those awesome months. :-P
BFP #1 9/7/10, EDD 5/14/11, Violet born 5/27/11.
BFP #2 4/9/12, EDD 12/16/12, M/C Rory 4/24/12.
BFP #3 10/6/12, EDD 6/16/12., Matilda born 6/17/13.
As with everyone else, the 28th.
My MIL was born on February 29th, she just chooses Feb 28 or March 1st, whichever is more convenient for it. But, since she's super uptight about anyone forgetting birthdays I always make sure DH and I call her on the 28th so she doesn't go ape sh*t.