In other words, she had to be of majority age (21 years old) at the time of the birth to fulfill this requirement.
.....Assuming Obama was born outside the US. And there are, so far, no witnesses attesting to his birth in Hawaii.
It is pointed out in Keye’s suit that the only person (no doctors, nurses, neighbors in HI ) who swears they were present at this birth is his paternal grandmother and she says the birth took place in Africa.