PRETERM BIRTHS

This indicator reports the percent of total annual births which are preterm. Preterm birth is defined as the delivery of an infant at less than 37 weeks of gestation, the period of time between conception and birth. Late preterm births (occurring between 34 to 36 weeks of gestation), moderate preterm births (occurring between 32 to 33 weeks of gestation) and very preterm births (occurring less than 32 weeks of gestation) are subsets of preterm births. Since 2014, preterm births have been calculated by establishing the gestational age based on the obstetric estimate. For years 2013 and earlier, the gestational age was calculated in the month prenatal care began by recording the date of the last normal menses. This change may lead to a slight discontinuity in prenatal care results between years 2013 and 2014.

Preterm birth is an important public health issue requiring sustained focus on its causes, consequences and prevention strategies.1 Several factors – economic, personal, medical and behavioral – including ones that researchers have not yet identified, may increase the likelihood that a woman has preterm labor and delivers early.2 Compared to infants born at term, preterm infants are more likely to suffer lifelong neurologic, cognitive and behavioral problems.3,4 Preterm births and low birth weight are often, but not always, associated. In 2010, infants born preterm accounted for two-thirds of all low birthweight infants and 46% of preterm births were low birth weight. In 2013, two-thirds (67.0%) of all infant deaths occurred to the 11.4% of infants who were born preterm.5 Preterm births cost the U.S. health care system more than $26 billion each year.6

• Preterm births accounted for 7.4% of the 38,610 births to Orange County residents in 2014, dropping 24.5% from 9.8% in 2005. By comparison, the rate for California was 8.3% (25.9% decrease since 2005) and the United States was higher at 9.6% (24.4% decrease since 2005) in 2014.

• Disparities persist with Black infants at 10.9%, followed by Asian (6.7%), Hispanic (6.1%) and White (6.0%) infants The percents decreased for all race/ethnicities, compared to 2005.

• Percent of preterm births was highest among women less than 15 years old (18.2%) followed by women older than 40 years of age (11.8%), 35-39 years (8.9%), 15-19 years (7.3%), 30-34 years (7.1%), 20-24 years (6.4%) and 25-29 years (6.3%).

Note: Percent calculated from number of births with known obstetric estimate gestational age less than 37 weeks for 2014. Rates prior to 2014 were calculated from last menstrual cycle dates.

March of Dimes Report

Note: Percent calculated from number of births with known obstetric estimate gestational age less than 37 weeks for 2014. Rates prior to 2014 were calculated from last menstrual cycle dates.

Note:

Woods rate is based on fewer than five births. Rates based on less than five events are unstable and should be interpreted with caution.

Source: Orange County Health Care Agency, Family Health Division