Lena's first word?

This has been bugging me for a while. What exactly constitutes a first word? When and how does the reconstruction of history occur regarding your firstborns? (I have gone from being certain nothing in their history would be tainted to understanding that the sleep-deprived mind is a very creative thing.) I remember hearing Nico calling mama mama incredibly plaintively, and asking Chris, "So is July 24 the day and Nico's first word mama?" It was so clear, I wanted to stop the car and say, "Yes, baby, I'm your mama, don't cry." But that would only have prolonged the crying by prolonging the time til we got home. This was after Lena had been mumbling mamamama for a couple weeks. But they weren't looking me in the eye or holding out their arms as they spoke.

The day before Thanksgiving, Lena seemed to speak purposefully. She was teething and using my nipple as a teether, so I had been saying, "Ow, don't bite," quite a bit. Then Nico fell on her head and started crying. Then Lena spoke--but did she really make such a sophisticated connection? See, I hesistate to assert that Lena's first word is "ow." (And, what are the poetic implications of such a first word?) However, this evidence may suggest otherwise: Lena's first word?