I agree they sometimes regress a bit when there's another baby on the way - my DD did and she was 2.5 so I was surprised. She'd been sleeping through the night, 13 hours a night, every night since about 9 months. About a month after DS came home she started waking during the night. We had no idea what had happened, it went on for months and months and only in the last month or so has she started sleeping through again every night. It nearly did our heads in, but looking back it was the only hiccup we had with her so we consider ourselves pretty lucky, I think she adjusted pretty well overall to her brother joining the family. She had other big changes around the same time too like changing bedrooms, moving to a big bed from her toddler bed, starting preschool etc.

Hang in there, it might just be a phase - I can't believe she's still doing two day sleeps, I think you're very lucky!! LOL.