If liberation from cyclic existence is not achieved during this intermediate state it comes to an end at the moment of conception. Since consciousness is said to possess certain heightened qualities during this period there is a potential to achieve liberation, or at the very least a favourable rebirth
This passage defines the intermediate state of rebirth as a temporally bounded condition in which heightened consciousness offers graduated opportunities for liberation or favourable re-embodiment.
, The Tibetan Book of the Dead (Penguin Classics), 2005thesis