cindylouwho, Time Warp is a different power than Grant Youth. The one that causes the problem is Grant Youth. Time Warp can be used to reverse the process, but it will take a few uses, depending on how old the villager was when she was made young.

Unless Arthur decides to revamp how the nursing timer works (and I'm not expecting that, given how complicated the nursing timers are), it is probably not a good idea to use the Grant Youth power on any female that you ever want to be a mom.