In the first bunker, it was said that a maximum of ten lives could be sustained. Any more and all would die of hypoxia. If the same rules applied in the second bunker, then the mandate to procreate would create new lives that could not be sustained if any children were born prior to the end of the year. And, even if the children were born after the characters exited the bunker, the pregnancies alone could cause too much extra drainage from the oxygen supply. Furthermore, if there were a greater oxygen supply in the second bunker, then there would have been no reason to limit the number of survivors to only ten in the game.