Heifers are tricky! Don't gauge by the udder because some (especially heifers) just aren't that big when they calve. She most likely won't calve until her teats start to fill/are full (sometimes not all the teats are full when they calve) but prior to that her hoo-hoo will swell, tail raised &/or to the side, she'll pace or show signs out of character and watch for the mucus plug. Watch her sides to see if the calf has dropped, getting into position (she'll look thinner). My girls always spend quality time at the protein tub just prior to calving and some of them start licking my jeans or grooming other cows - hormones kicking in. If you have her contained you can keep an eye on her, otherwise she may start looking for a place to calve. If you're fairly certain she's due in March I wouldn't worry unless/until you see the signs. Keep us posted & good luck!
