Short Inter-Pregnancy Intervals in the United States: Results from the 2006-2010 NSFG

Alison Gemmill, University of California, Berkeley

Short inter-pregnancy intervals (IPIs) are associated with a number of negative outcomes for both mother and child, yet there has been little systematic surveillance of IPIs in the United States. We use data from the 2006-2010 National Survey of Family Growth to investigate the prevalence and correlates of short IPIs, defined as pregnancies that occur within 18 months of a previous birth; analyses are restricted to pregnancies occurring within 5 years of the interview date. Among the 3,054 pregnancies in our sample, 36% were classified as having short IPIs. After adjusting for socio-demographic and childbearing characteristics, women were significantly more likely to have a short IPI if they began childbearing after age 30, had higher parity, or had a mistimed or unwanted pregnancy. Given the association between IPI length and pregnancy intention, we find that preventing unintended pregnancies would reduce the proportion of short IPIs from 36% to 22%.