As predicted in a previous post the Impossible Astronaut was all but revealed to be the hybrid daughter of Amy and the Doctor in the subsequent Doctor Who episode “Day of the Moon.”
In a deserted orphanage, Amy discovers old photographs of the girl in the space suit, including one of Amy holding her as a baby. At the end of the episode, Amy tells the Doctor that she was mistaken about the pregnancy but unbeknownst to her, he uses the TARDIS to scan Amy.
The pregnancy test is inconclusive, altering between positive and negative. This may be normal for a Time Lord pregnancy, however the space suit the Time Lassie wears contains a life support system and once out of it she dies and regenerates. This seems to indicate instability. Perhaps the results are indeterminate because the Time Lassie is from a possible timeline. In other words, she is of one of those unfixed moments.
Remember, the Doctor who set all this in motion was from 194 years in the future. There’s also the matter of the mysterious Fake TARDIS, which attempts to go back to the future in “The Lodger” and reappears in this episode.
But before this Time Lassie fades away a la Marty Mcfly, it’s only fitting she have a name and what better name than May because she “may” be Amy’s daughter and it’s an anagram of Amy.