Yeah, the simple act of creating the life doesn't have utility in any interpretation, I think; people just talk about the utility of procreation as a sort of Net Present Value on the projected utility that life will experience. Under positive utilitarianism, all lives either experience positive or zero utility, so it's never a net negative to have more of them.

Most positive utilitarians further posit that all [evolved, rather than maliciously-engineered-for-the-sake-of-cruelty] lives likely contain at least a little happiness/reward/satisfaction (positive utility), and since the unhappy moments just axiomatically have zero utility, rather than negative utility, all [evolved] lives should "sum up" to being worth creating from their own perspectives—though creating additional lives might make marginal global utility go down, for Malthusian reasons (ten starving wolves that each live for a year aren't don't have as much utility as one well-fed wolf that lives for ten years.)

Personally, I don't like positive utilitarianism very much—but it's important to understand, since it seems to be the intuitive stance a lot of (often religious, but not always) people have without realizing it.