There are no 2nd calf "heifers." But watch her. If she seems to really get labor started and then shuts down, you should bring her in and check her. That's something that can happen with first-timers, but if there's a bad presentation, you could have an issue with a cow. I am the Nervous Nellie at our place, and if we suspect a cow due soon we've not much calving history with, we usually bring her in to a pretty good sized pen that has shelter and check her several times/day. Not minute by minute. Our "experienced cows" we pretty much leave them alone and let them do their thing; we watch when they're close, but don't bring them up to the barn.