You are talking about the difference between weighted and unweighted frequencies. There is a fundamental misunderstanding of the weights here. When you do not use weights, you get the unweighted number of cases in the data. When you do use weights, you get the weighted number of cases in the data. They do not match. The weights have been constructed in such a way that in the IR file (PKIR61FL.dta) the total number of weighted and unweighted cases will be the same. You can check this with the IR file by comparing "tab v007" and "tab v007[iweight=v005/1000000]". Both of them will give a total of 13,558 women. The mother's weights (v005) have been transferred directly onto the KR file. Within the KR file, the corresponding totals will NOT match. If in the KR file you enter "tab v007" you will get an unweighted total of 11,763 children. If you enter "tab v007[iweight=v005/1000000]" you will get a weighted total of 11,977.381 children. These two numbers are different, simply because the number of children born in the past five years is not statistically independent of the weight variable. The difference is very small, but some difference is virtually inevitable. The weighted number of cases is not a "population size". Proportions and means calculated with weights will be better estimates of population characteristics than the UNweighted proportions and means would be, but you cannot interpret a weighted frequency as a "population size."