Interpregnancy Intervals in the United States: Data From the Birth Certificate and the National Survey of Family Growth

A new NCHS report looks at data on interpregnancy intervals (IPI), defined as the timing between a live birth and conception of a subsequent live birth, from a subset of jurisdictions that adopted the 2003 revised birth certificate.

The data contains births to residents of the 36 states and the District of Columbia (DC) that implemented the 2003 revision of the birth certificate as of January 1, 2011.

Because this information is available among revised jurisdictions only, the national representativeness of IPI and related patterns to the entire United States were assessed using the 2006–2010 National Survey of Family Growth (NSFG).

Key Findings from the Report:

• Jurisdiction-specific median IPI ranged from 25 months (Idaho, Montana, North Dakota, South Dakota, Utah, and Wisconsin) to 32 months (California) using birth certificate data.
• Unmarried women had a higher percentage of long IPI from the birth certificate and NSFG compared with married women.
• Consistent patterns in IPI distribution by data source were seen by age at delivery, marital status, education, number of previous live births, and Hispanic origin and race, with the exception of differences in IPI of 60 months or more among non-Hispanic black women and women with a bachelor’s degree or higher.