Hello Eric. Perhaps you’d like to let your wife try pregnancy pillow?
https://www.google.com.sg/amp/s/sg.theasianparent.com/best-pregnancy-pillows-for-back-pain/amp
Sometimes in second trimester will cause insomnia which is normal and in third trimester will be even more difficult to sleep comfortably due to big stomach/ the weight it’s normal too.
Maybe you can fix her a cup of chamomile tea for her to sip a little before bed time.
Ginger