An Honest Question
 

I would tend to think that a small dog is a small dog and the risks would be the same no matter what breed you had.

I agree all small animals no matter what they are need to be carefully watched.

In a word, yes.

Chihuahua: Avg litter size: 2-5, Avg Birth Weight: 3-5oz, pups as small as 2 oz survive. Standard Deviations: open fontanels common & ok by the standard. malocclusions, retained baby teeth.
Reported disorders: 20
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Yorkshire Terrier: Avg litter size: 1-4, Avg Birth Weight: 4-6oz, Standard Deviations: no fading-failure of black hair to turn steel-gray by 1yr. Malocclusions, retained baby teeth.
Reported disorders: 20 (share about 1/3 with chi)
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That's from Successful Dog Breeding by Chris Walkowicz & Bonnie Wilcox DVM
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So, if those are the averages, where you might start to have real concern is with any pups born substantially below average. Most of the puppies that we have had were close to 5oz. We had one 6oz (Now 5lbs) & one 8oz (now 12lbs).

I think it's the case with any female dog. If the pups skulls are larger than the pelvis opening that they have to come out through you're going to have a c-section. I've learned alot from my vet here and my mentor. I have a friend with a 11 lb chi. She was from a litter of 2 and was a large pup.
My Maggie had a litter of 2. One was 6oz and the other was 8oz. It was not an easy delivery for either, the bigger puppy was harder to deliver and she was stressed.
When we started to breed Sunnie, we had moved here & my vet talked to me about wanting to have as many viable eggs fertilized as possible. The greater number of puppies the more consistent the birth weight. When she went for her checkups he monitored her progress and when he only felt 2 babies he also monitored her diet to keep them from getting too big. We did an x-ray at 60 days to check position, head size compared to the width of Sunnie's pelvis and placement. We had good results and a good delivery.
My mentor had a litter of 6 a year ago. The smallest was 2.5oz and the largest was 8oz. That same female has had a litter of 7 the year before and they were all between 3.5 & 4.5 oz.
You raise some good concerns. When there's an average litter size of 1-4 you could run a pretty good chance of having a large pup once in awhile.

Oh, that's ok you can ask. A BOA is a Branch Office Administrator. I'm not full time anymore I am an on-call for an investment company. Like an in-house temp. It's just a couple of days a month.

I've learned as much as I can about whelping. I faint if I cut myself but I can do puppies. Go figure.