Income Group | Sample Size (N) | Mean IBI (months) | SE (months) | Modal IBI (months) |
---|---|---|---|---|
Middle-income | 29,016 | 30.5 | 18.5 | 24 |
Low-income | 33,949 | 27.0 | 13.0 | 26 |
Natural fertility | 276 | 34.9 | 19.7 | 24 |
US WIC nonparticipant | 438,441 | 39.8 | 24.3 | 21 |
US WIC participant | 331,128 | 41.5 | 26.8 | 21 |