Re: wife pregnant 6 years after miscarriage
Most miscarriages are caused by random genetic defects incompatible with life.
The defect may be with the egg, or the sperm, or both.
I say 'random" because every woman has some genetically flawed eggs (more and more as we age), and every man has some genetically flawed sperm.
So it's like a lottery: it's just luck of the draw. You guys happened to draw the black ticket.
There's no reason to suspect it'll happen again, if everything else checks out.
In fact, your chances of having a second miscarriage are slim... except for the fact that your wife is six years older now, and the older a woman is, the fewer viable eggs (and the more flawed eggs) she has. But if she's under 35, chances are she's fine, the egg was viable, and this pregnancy will continue to term. Even if she's under 40, she's got a pretty good shot. Over 40, the odds are not so good.
I'm 38 years old and 7 weeks pregnant.
I've got a lot of the same concerns, but que sera, sera. I've known all along this wasn't a sure thing.
best of luck.