Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.
FP1STUSGPKID (V311) reports the number of living children, if any, the woman had when she first used a contraceptive method, with the number top-coded at 4+ children. FP1STUSLVKID reports responses to the same question, without top-coding the answers.
When children are chosen as the unit of analysis, the woman respondent indicates the mother of the child.