converting word to PDF: losing characters within figures

When I convert a Word document with pictures to PDF, the text characters in the figures are lost, but the pictures are still there. In Word, it seems to be just one picture, with some letters and numbers next to black and white figures. Does anyone know why only part of the picture would write to PDF, and if there is anything I can do to make sure the whole thing is converted? I have tried in Word, printing to PDF, and also opening Acrobat and selecting 'create from document', but the same thing happened in both cases. Thank you!