I haven't bred at all for the last 2 years due to the economy but I have 2 thoughts on the matter of trailering youngsters.
1. I've lost 3 babies in my breeding career and none of them were due to trailering. All my babies to date have gone to inspections and been registered.
2. Trailering at the young age gives the babies an early experience getting into the horse trailer and I've found this to be very positive when the babies are a little older.
While I agree that trailering babies is dangerous, I would also agree that trailering horses of any age is dangerous. I do plan to breed a couple mares next year and I will take the babies to their inspections.