
I believe most reabsorbing takes place around week 5. One of ours looked well in whelp (I don't do scans, preferring to wait) by that time into her pregnancy but simply didn't grow any bigger. She had one puppy so at least we did have one!! That bitch only had 2 in her first litter, so she wasn't exactly a prolific bitch which surprised me as of the two litter sisters we'd kept, she always looked like the btter brood bitch prospect. Her prima donna sister, who took her Championship, always overshadowing her sister in the ring, had 9 puppies although due to veterinary incompetence (he refused to do a C.Section) - long story, 5 of the 9 were lost on delivery. Healthy puppies, just lost because of the delayed 'Section.
ps There was no sign of any reabsorbing having taken place, when she was opened up to deliver the singleton puppy and our vet was doubtful that had happened.