Does deleting a partition below Ubuntu mess up grub?

[Colin Law]

I want to delete a partition (sda4) which is below the Ubuntu
partition (sda5).  I seem to remember when I did something similar
some time ago that it messed up grub and the machine would not boot,
due to the fact that the sda numbers changed when the partition was
deleted.  Is that still the case, and if so is there a procedure for
deleting sda4 that will not cause such problems?  This is Ubuntu
12.04.

Cheers

Colin