This question comes up a lot. I just answered a doll maker who inquired about the Nurses uniform. Since this answer applies to any pattern, I thought I would post it here, too. You may find it helpful.
Even though two dolls are the same height, they may have different body shapes, and different length arms and legs.
Shown above are Faith, Hope, and Gracie, left and Joy, right.
I would suggest comparing the pattern pieces for the dress, with a dress pattern that fit's the doll you wish to make the uniform for. Either adjust the pattern for the uniform dress or make a similar dress using the pieces from the dress that comes with your doll. Does that make sense?