Whoda thunkit? Maybe any rancher, dog breeder or vet. The effect of overlong intervals between pregnancies is a bit of a surprise. This is the first serious non-economic, non-social counter to the "Mo' baybeez gotta be better!" argument that I've seen. Of course, the health argument will backfire in certain quarters, because having a premie brings in more welfare, in addition to the major pity-party that momma gets to throw.