| Value | Category | 
|---|---|
| 0 | No flag | 
| 1 | Greater than interval between birth and succeeding birth | 
| 2 | Greater than interval between birth and date of interview by only 1 month | 
| 4 | During pregnancy in calendar | 
| 8 | Missing | 
| 9 | NIU (not in universe) | 
| var_concept.title | Vocabulary | 
|---|---|
| General maternal and infant health Variables -- TOPICS | IPUMS |