Seat recommendations for pregnancy?

We plan on flying LHR -IAD in the first week of June, and I will be 21 weeks pregnant. I have close to 50K in VA miles, and was thinking of using them to upgrade.
As the first flight is during the day, I was trying to decide between getting a seat in Economy with extra leg room so I can get up and move around a lot or upgrading to PE. For the return flight, upgrading to UC so I can lie down seems a no brainer.
I have not bothered to upgrade before as I am not a big person and Economy has always been doable. I do get really bad swelling in my ankles though, and can only imagine how much worse it may be being pregnant. Is the difference between economy and PE worth it?
Would appreciate any thoughts and insights.
As the first flight is during the day, I was trying to decide between getting a seat in Economy with extra leg room so I can get up and move around a lot or upgrading to PE. For the return flight, upgrading to UC so I can lie down seems a no brainer.
I have not bothered to upgrade before as I am not a big person and Economy has always been doable. I do get really bad swelling in my ankles though, and can only imagine how much worse it may be being pregnant. Is the difference between economy and PE worth it?
Would appreciate any thoughts and insights.
