Definition
BIRTHTOHHRES2YRNO reports the number of births to usual household members of this household during the past two years, "in this city/town/village or outside." Presumably some usual household members died or moved in the two year interval, so they may not still be household residents at the time of the survey.
The related variable BIRTHTOHHRES2YR indicates whether there were any births to usual members of the household during the past 2 years.
The information in BIRTHTOHHRES2YRNO is taken from the household record and applies to regular household residents, not temporary visitors. Researchers may wish to exclude visitors using the RESIDENT variable (with visitors coded "2") when women, children, or births are the unit of analysis, and using the HHRESIDENT variable when household members are the unit of analysis.