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March 19, 1997

State-Specific Variation in Rates of Twin Births—United States, 1992-1994

JAMA. 1997;277(11):878. doi:10.1001/jama.1997.03540350028014

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DURING 1980-1994, the number of twin births in the United States increased by 42%, from 68 339 to 97 064, and the twin birth rate (i.e., the number of twin births to total live births) increased 30%, from 18.9 to 24.6 per 1000 live births. These increases are important because the risks for preterm birth, low birthweight (LBW), long-term disability, and early death are greater for twins than for singletons (1; CDC, unpublished data, 1991). To estimate state-specific rates of twin births, CDC analyzed data from the U.S. certificates of birth for 1992-1994. This report presents the findings of this analysis of these data, which indicate that state-specific rates of twin births varied substantially, and the variations reflect factors other than state-specific differences in maternal age distributions.

In this analysis, twin births were defined as individual live births in twin deliveries, rather than