Eggs from first-year females

Here's a question for those of you who have obtained second-generation CB offspring... When you get eggs from a female that is in her first year of reproduction, how often do you have problems raising the offspring? (And, if so, how could you tell if the problem was due to inbreeding versus female age?)

I am currently having really bad luck with raising eggs from my first-year M. alpestis. Also, another person I know is having difficulty with larvae from a first-year T. marmoratus. In both cases, the eggs and embryos look good, but the larvae die just after hatching or a few days later when they should be starting to eat.

I seem to recall having problems of this kind before, but I didn't keep any records to help me remember if the problems were really associated with first-timers. Last year with my Cynops and Neurergus, the first-time females produced some infertile eggs, but the larvae were perfectly healthy.

In my experiences, it's been common to have infertile eggs, from just a few to all infertile, but I've never had widescale problems with the fertilized eggs as well. I'd definitely be more inclined to attribute the problems to a young female rather than inbreeding. I suppose next year will be the final answer though, eh?