In a domestic situation with a breed that doesn't like heat I find I much prefer a heat pad under th Vet bed so pups can move to it, but the bitch can keep away.

In the bedroom at night I provide background heat for the litter using an oil filled radiator next to the whelping box.

With a lamp you have to have some way of suspending it ( I am not a handy person), and move that from one place to another as the pups move from bedroom to kitchen/living room. the heat pad is unobtrusive.