It's a question that comes up from time to time and the only right answer is that 'it depends'. More specifically, you will get a bit more legroom and seat width to use, but how much you or your wife value it relative to the cost of the upgrade, is a decision only you can make.

So for example, way back in the day,
my wife flew long haul in economy whilst pregnant with both our children (the second time, one of them was in a bassinet cot, just to add to the fun). On one occasion she was at 32 weeks and we got interrogated after boarding to ensure she had the appropriate doctors letter!

But I digress, back then neither of us even considered flying a higher class, despite being very financially able to do so - to be fair, she was significantly smaller than me even while heavily pregnant. That said, I wasn't the one getting internally pummelled!

Fast forward to today, and I wouldn't even consider travelling anywhere LH in economy. That's partly the effect of getting old and soft (and seeing the benefit of nicer seats from work travel), but also partly the effect of hanging around these boards, which can act as a bit of an echo chamber for the premium cabins... you have been warned!

So that's my very long winded way of saying... yes, nicer seat, but no, we can't do the cost benefit analysis for you! Although if you give us the cost for upgrade, we can at least say whether it's relatively cheap or expensive...

Actually, sod it, it's your wife, do the upgrade. With age and hindsight, I wish I had all those years ago!