There's a colony of feral cats living in my neighborhood. At one point, a small tuxedo was pregnant and a while later everyone heard meows for days...then they stopped. Nobody could find the kittens. I think undernourished mama couldn't feed them.
We decided that wasn't happening again, not if we could help it. We started feeding them. "If you give a mouse a cookie" is a true principle, but that's okay. Cat food isn't expensive and they needed looking after. Mama cat, who we call Jojo (short for Josephine) got pregnant again. I've looked into spaying programs for strays and it looks like we'll be able to fix her problem and extend her life once kittens are weaned. This litter survived and now lives on our back patio until we can get them weaned and to a rescue program. We're working on socializing them in the meantime.