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Average Duration of Pregnancy, by Number of Births (per Pregnancy)

Expecting more than one baby? Work with your health care provider to minimize the risk of premature birth.

Chart: Average Duration of Pregnancy at Birth, by Plurality, United States, 2005.

Gestation (duration) is the timeframe beginning with the first day of the last normal menstrual period and ending with the day of birth or day of termination of pregnancy. Normal gestation is considered to be between 37 and 41 weeks. Shorter gestation is associated with poorer birth outcomes, long-term morbidity, and higher infant mortality rates. The risk for shorter gestation is greater with multiple births than singleton births. In 2005, the mean gestational age for singletons was 38.7 weeks, compared with 35.2 weeks for twins, 31.9 weeks for triplets, 29.8 weeks for quadruplets, and 27.4 weeks for quintuplets and higher.

Data Source:

National Vital Statistics System. 2005 natality file. Available at http://www.cdc.gov/nchs/births.htm.

Citation:

Centers for Disease Control and Prevention. QuickStats: Mean Gestational Age, by Plurality --- United States, 2005. MMWR 2008;57:09(238).

More Information

  • Page last reviewed: November 14, 2008
  • Page last updated: November 14, 2008
  • Content source:
    • Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs
    • Page maintained by: Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs
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