Question
Is there any problem leaving last spring Koi babies outside. I live in the New York area. Over the last two weeks i lost 6 babies. The pond is above ground about 30" deep with insulated walls.

Answer
If the pond is overwintered properly, the babies should be large enough that a good many will be able to survive.  The fact that you've lost 6 is not a good sign.  Your pond would be deep enough except it's above ground.  How many gallons is the pond?  Do you use a de-icer, aerator, pump, etc. during the winter?  Have you overwintered adult koi in the pond okay?  How many fish are in there?  You can e-mail me from my site if you want to discuss this further.  My page on overwintering ponds is at http://www.fishpondinfo.com/winter.htm
The baby koi have a little higher oxygen demand and will not do so well if the pond is too low in oxygen over the winter.  Many koi keepers bring in the fry of the year for the winter so they can put on more weight and be more likely to survive.  If you have a lot of babies, you will lose some.  In the pond, it's survival of the fittest.  Good luck!