No, I didn't mean the engagement band was being resized to accommodate swelling of her fingers during pregnancy!
The band was resized though -- that's what Omid reports.
So, per Omid's report, my speculation is that the band on the engagement ring was always slightly loose as it seemed to move around a bit on Meghan's finger. That could have been due to her losing a bit of weight in the lead-up to her wedding. Who knows?
Or else, Harry, Meghan or both wanted the band changed to a more delicate-looking diamond band, and it necessarily required resizing because of the change in band design and material.
As far as the temporary swelling associated with Meghan's pregnancy, I meant that because she had to remove her rings, that was a good time to have the band resized to accommodate the change Harry was having made (either as a surprise, or else Meghan knew about it).
We noticed in the latter days of Meghan's pregnancy, before she disappeared from public view, that she was not wearing her engagement ring. Some speculated it was because of possible swelling. We don't know that since it hasn't been confirmed.
Whatever the case, the ring was probably resized and the band was changed around the same time that Meghan was in the latter stages of her pregnancy. And probably when Harry presented Meghan with the eternity ring for their wedding anniversary on May 19, he also gave her back the engagement ring with the new diamond band. This is speculation based on the recent reports that have been published.