Early season hatching eggs=less thrifty ducklings??

[FenDruadin]

Just wondering--has anyone noticed a correlation between early season eggs and low hatchability and/or unthrifty ducklings? I ran a batch early this spring in which all the eggs completely failed to develop (probably infertility, though I had broken several eggs and thought they were fertile, but anyway--). I then ran a test batch of only four eggs, a couple weeks later. Two were fertile, so it was an improvement but still not a very high percentage. Of those two, both developed all the way to lockdown, but only one hatched. The other pipped internally but never pipped externally. The one that hatched had to be helped with the zipping (it pipped fine and got half zipped and then got stuck--I waited about four hours from when progress stopped, and finally chipped away a semi-circle of shell and let the duckling finish the popping). It appears vigorous, but one wing is cocked at an odd angle and I wonder why it had so much trouble with zipping.

I'm wondering if the low hatch rate (50%, although I realize a test batch of two is hardly a scientific sampling) could have anything to do with the earliness of the season in which I collected the eggs. Is it possible that defects could occur because the ducks are just gearing up for the season?

I have another batch of 22 in there now, so I should have a better sampling to see if I have bigger problem, but I hope not! I'd love to hear someone tell me that it's common early in the season to have those problems. If so, then I won't try hatching so early again!

Thanks for any thoughts--