This discussion may contain spoilers!
If Kenny's desire to protect the baby is the main concern for the episode, then Jane's desire to "protect" (?) Clementine is the subtext. She even states it as the major reason that she came back to help the group, but I doubt anyone here understood the depth that Jane would go to prove her point. If the baby was everything to Kenny, then Clementine was slowly, but surely, becoming everything to Jane.
It is claimed that Jane cares about no one other than herself, which is strictly not true...at least not anymore. Ever since she lost of her sister, Jane mainly cared about herself. However, Clementine stirred Jane's sisterly feelings. Jane realizes this when she felt guilty about threatening Arvo and killing the Russian. However, I think Jane accepted that she wanted Clementine around.
As much as I like Jane when she is the voice of reason (only WHEN), if Kenny survives and you leave with Kenny, he gives the baby and Clementine up for the sake of their protection. As much as people talk about Kenny's mental state, and how he thinks he is emotional and "always right", he is not possessive. When he believed someone or something else could protect the ones he cares about, he will let go. He just has to have enough faith and trust in it. However, I do believe there is one major difference.
To prove she both normally cares about mostly about herself AND that her desire to "protect" (?) Clementine had warped her rationality. She hides the baby in an empty car. The normal Jane might have just left the baby there and walked. Another person would have ran away and taken the baby away from Kenny. Another would have just given the baby to Kenny. However, these dual aspects within her, she created a situation where she put the baby in danger, herself in danger, and push Kenny over the edge.
I think it was an incredibly stupid thing to do, especially for a person that is normally rational like Jane. She could have avoided the situation entirely. Jane did what she did for entirely selfish reasons. However, I do think we need to understand WHY she did it. Despite what Jane says, she regrets leaving her sister behind. Her desire to "protect" (?) Clementine implies this was always eating at her. I am not excusing her behavior, by the way. I'm just wonder out loud on what happened and why she did it.