As far as I know when women have kids their body can pretty much not care about sex any more since as far as it's concerned sex is only for reproduction. Birth control pills and other types of medication are also well known for killing a woman's sex drive. (ironic huh?)

Being tired will also have dramatic effects so I doubt you can just force it at that time.

Talking to your doctor about it is probably a good idea. I am very doubtful that it comes back on it's own and you guys may have to get proactive about it. But it is possible to get it back.