Following is a response from DHS staff member, Tom Pullum:
Here is a Stata program to merge the PR and IR files. It differs only slightly from the one to merge the HR and PR files.
* Specify a workspace
cd e:\DHS\DHS_data\scratch
* Prepare the PR file; keep only the household-level variables
use "...IAPR7EFL.DTA", clear
* Reduce to eligible women
keep if hv117==1
gen cluster=hv001
gen hh=hv002
gen line=hvidx
save PRtemp.dta, replace
use "...IAIR7EFL.DTA", clear
gen cluster=v001
gen hh=v002
gen line=v003
merge 1:1 cluster hh line using PRtemp.dta
* Some women were eligible but were not interviewed (nonresponse cases); drop them
tab _merge
keep if _merge==3
drop _merge