We did the medical without the x-ray and sent this to CIC with a note indicating Anna was pregnant and we would do the x-ray at a later date.  Because of the lengthy process of the inland application, I'm not convinced that delaying the x-ray until after birth made any difference at all to the timeline.  No way to know for sure.  We did the x-ray one month after she gave birth.  She landed about 3 months later.