Pregnant women, as a rule, don't have milk. There's a thread around here somewhere that covers the whole business. Suffice it to say that progesterone, the hormone that starts lactation, also kick starts labor. There's more, but ya'll have search engines.
Maybe a woman whose already had a baby. Like an older baby, cause the first couple of months after the kid, well, it's kinda like a 4 inch PVC pipe in there, if you know what I mean.