Birth age meaning "your actual real age from your actual real date of birth," clearly.

But where's the fun in thinking that far?

Technically speaking, your birth age would almost always come out to 4.5 months.

The Supreme Court still hasn't ruled on that, though prevailing opinion is that legally, life begins at second base.

Either way, your logic is flawed. Birth happens roughly nine months after conception.

Birth and life are different according to most coourts

Anyway, who says all these races have a nine-month gestation, particularly given that some of them lay eggs? (Is the 'birthday' for an oviparous species the date of laying or hatching?) And while we're being absurdly technical, a human gestation period in Lusternia would be around 11 months, since Lusternia's months are notably shorter than Terra's.

Oh Geez. You know, it wouldn't surprise me that much if there really were people who thought that way. That's when you made a commitment etc etc etc.

You know, this is all nice and everything, but in the game of Lusternia, I need to have been a teenager to have my kids, and if I can somehow skip the whole "high school" stage of life, and get to makin' babehz, then I will! I want ageing to affect families like it's supposed to, plz!