After almost 20 years of steadily increasing, induction of labor for singleton births in the United States declined in 2011 and 2012, according to a new report published online June 18 by the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.
Report authors Michelle J.K. Osterman, MHS, and Joyce A. Martin, MPH, from the CDC's National Center for Health Statistics, detail trends in induced labor for singleton births by gestational age, race, Hispanic origin, and state for 2006 through 2012. Singleton births accounted for almost 97% of births in 2012. The report excludes multiple births because of differences in management of labor and delivery.
Overall, induction of labor shot up from 9.6% in 1990 to 23.8% in 2010 and then edged down to 23.7% in 2011 and 23.3% in 2012.
The proportion of infants born at less than 39 weeks' gestation rose almost 60% between 1981 and 2006, whereas the proportion of births at 39 weeks or longer declined more than 20%, the authors write. They attribute the trend to greater use of cesarean delivery and induced labor before full term.
Since 2006, however, births at less than 39 weeks are down by 12%, and births at 39 weeks or longer are up 9%.
Among early-term births for 2006-2012, induction rates declined the most for gestation week 38, down 16%, and week 37, down 6%.
Among late preterm births (weeks 35 - 38), induction rates declined 3% at 35 weeks and 7% at 36 weeks, whereas induction rates at 34 weeks went from 15.9% in 2006 to 16.6% in 2010 and 2012, for an increase of 4%.
Those rates varied by maternal age. For instance, for women younger than 20 years from 2006-2012, induction rates for week 38 declined about 5%, but induction rates for weeks 35-37 increased 5% to 10%. Induction rates were steady among women older than 40 years.
Race and Hispanic Origin
For induction at 38 weeks, rates declined 19% among non-Hispanic white women (from 25.9% to 21.1%), 3% among non-Hispanic black women, and 7% among Hispanic women.
Rates varied for induction at weeks 35 to 37. For instance, rates for non-Hispanic white women declined between 6% and 11%, whereas rates among non-Hispanic black women increased at least 5% at weeks 35 and 37 and were unchanged for week 36. Rates were steady for Hispanic women.
Differences by State
Rates declined 30% or more in 5 states, with Utah having the sharpest decline at 48% and Maryland having the least decline at 5%. Rates inclined at least 10% in 31 states and the District of Columbia.
Rates increased for week 38 in Alaska by 33%, New York by 11%, and North Carolina by 9% for 2006 to 2012 and were steady in 11 states.
The authors base their report on data from the Natality Data File from the National Vital Statistics System, which contains information on maternal and infant demographic and health characteristics for all births in the United States.
"Recent Declines in Induction of Labor by Gestational Age." NCHS data brief 155. Published online June 19, 2014. Full text
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Cite this: Induced-Labor Births Are Trending Downward, CDC Says - Medscape - Jun 18, 2014.