Awww but you see, many of these life threatening situations CAN'T be prevented! There are many many ill fates that await those that breed with Mother Nature having the final say. There is no magic wand to touch and make it all okay. The risks that are being mentioned happen all the time and only the most knowledgable can work with them. NOT prevent them.
As Christina points out, as nice as it would be to tell people what to do to prevent the tragedies, it can't be done in a 6 paragraph internet post, or even a textbook of dog midwifery (there are several. I found them virtually useless with my orphans. Good on the mechanics of pregnancy and delivery, not much help in what the hell do you do when tragedy strikes).
Probably the best one can do in THIS environment is to drive home that if you don't know the length of gestation of the animal you've just bred, you haven't even BEGUN to know the extent of the problems you may have to deal with suddenly.
How do you deal with emergencies? First you have to recognize what's "normal." Textbooks will help to a certain extent. But a lot of times the textbook advice is "call your vet and discuss." Unless you know what's pertinent and what's not to mention to your vet, he/she may miss a vital clue. Unless you know what's normal/what's not, you may not call the vet at all, or call too late.
Next it helps to have expert advisers. And that means people who will rush to your home to spend the night when the bitch gets close, or take your call at work to tell you what that color mucus probably means, etc. Such a person will know that your vet's well intentioned suggestion that the bitch be spayed immediately post whelping is likely to kill her, and no sensible vet would do any such thing (but they do anyway, and often).
That's not vet bashing -- but most vets don't deliver all that many puppies, and they're working from their own textbook reading, and not practical experience. I got some xeroxed pages about dietary supplementation and the assurance that it was okay if most of them died, because that was nature's way. Breeders told me there was no reason they couldn't all make it, and the best way to ensure that they did. Some came to my house with older bitches of their own, in hopes that these good dams would take to the orphan pups and at least clean and nurture them if they couldn't feed them. It didn't work, but I sure appreciated the way they went above and beyond to try.
A support network of knowledgeable people is critical when you don't have the experience under your belt.
As for Mother Nature, even in human beings, women deliver alone in log cabins or in the back of taxi cabs and do just fine. They also die from strokes and hemorrhage in million dollar birthing suites in top hospitals with a half dozen highly trained OB-GYNs within arm's reach.
