Should I feel guilty for taking this?

Last week, I excitedly pulled into a parking spot reserved for expecting mothers and customers with infants.  And then I began to wonder, "Is Liam still an infant?  Am I allowed to park here?"

I realize that he's no longer a newborn, since that title is probably reserved only for little ones who are within the first 3 weeks of life.

He's definitely still a baby, since a recent television commercial explained that a baby's a baby until he turns one year old.

But...is he still an infant at 4 months old?  Moreover, should I have taken this parking spot?  I have no idea!