Glofish dying?

First off I know some people are against glofish and that's OK to have your own opinion about them but that's not what I'm wanting to discuss here.

I originally started out with 6 glofish. My first one was heavy with eggs but soon died. I figured with it being just days after getting her, perhaps it was stress. Well several weeks later another female became heavy with eggs then died during a PWC though this was a daily routine since I was/am cycling. I'm just wondering if anyone else has noticed this in the glofish or even zebra danios? Is this common or have I just had a few strikes of bad luck? I am wanting to find out so if it is actually a defect in glofish, I will know to not buy anymore as I don't want to support the breeding of a defect in any fish of any kind.

The thing that gets me is that zebras (which glofish were made from) are very hardy fish. I wonder if the gene alteration has effected this hardiness?

Well there is always the possibility that my two died from stress. The first died 2 days after I bought her but from the time I brought her home, she stayed at the top of the QT tank. The second died right in front of me during a PWC. It could be possible that it just so happened that both where heavy with eggs when they died. Then again, it could be that even though just a gene was added, perhaps this hindered them in some way. That's what I'm trying to find out now.

I'm pretty sure that I have one male and three females left though from what I've been told, its hard to tell for sure. Anyways, none of the others are egg heavy yet.