Nikon D800 or Oly OM-D?

With 45mm, depending on the spaces in your house, you might find yourself backing against the wall. It might also be a bit difficult taking picture of the baby in the crib from the top. I would suggest 25mm 1.4 to start with.

Also, I usually don't get too far away from my baby girls (indoor and outdoor), so the 25mm worked out well.