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Low Birthweight and Preterm Births


Infants Born at Low Birthweight: 2009 See Source and Notes

Region Percent
California 6.8%
Region Percent
Alameda County 7.1%
Alpine County LNE
Amador County LNE
Butte County 5.6%
Calaveras County LNE
Colusa County LNE
Contra Costa County 6.6%
Del Norte County LNE
El Dorado County 5.8%
Fresno County 7.1%
Glenn County 5.0%
Humboldt County 4.7%
Imperial County 5.9%
Inyo County LNE
Kern County 7.4%
Kings County 6.4%
Lake County 5.5%
Lassen County LNE
Los Angeles County 7.3%
Madera County 6.3%
Marin County 6.1%
Mariposa County LNE
Mendocino County 6.2%
Merced County 6.9%
Modoc County LNE
Mono County LNE
Monterey County 5.9%
Napa County 6.3%
Nevada County 4.4%
Orange County 6.6%
Placer County 5.3%
Plumas County LNE
Riverside County 6.5%
Sacramento County 6.9%
San Benito County 4.9%
San Bernardino County 7.2%
San Diego County 6.7%
San Francisco County 6.7%
San Joaquin County 6.9%
San Luis Obispo County 5.7%
San Mateo County 6.7%
Santa Barbara County 6.2%
Santa Clara County 7.2%
Santa Cruz County 6.1%
Shasta County 5.9%
Sierra County LNE
Siskiyou County 5.0%
Solano County 6.9%
Sonoma County 5.9%
Stanislaus County 6.6%
Sutter County 5.7%
Tehama County 4.8%
Trinity County LNE
Tulare County 6.2%
Tuolumne County LNE
Ventura County 6.0%
Yolo County 4.8%
Yuba County 5.6%

Definition: Percentage of infants born at low birthweight, which is defined as less than 2,500 grams.

Data Source: California Department of Public Health, Center for Health Statistics, Vital Statistics Section, CD-Rom Public Use Birth and Death Files and Vital Statistics Query System.

Footnote: LNE (Low Number Event) refers to data that have been suppressed because there were fewer than 20 cases in the numerator. Data exclude infants for whom birth weight information is missing.

Learn More About this Topic

Measures of Low Birthweight and Preterm Births on Kidsdata.org

Kidsdata.org offers the percentage of infants born at low birthweight, by age and race/ethnicity of mother. Low birthweight is measured by the percentage of babies who are born at less than 2,500 grams (or about 5 lbs, 5 oz). Also available is the percentage of infants born at very low birthweight. Babies with very low birthweight are born at less than 1,500 grams (about 3 lbs, 3 oz).

The percentage of infants born preterm is available, as well. Babies born before 37 completed weeks of pregnancy are considered premature or preterm. More than two-thirds of low birthweight babies are born preterm (1).

Source:

  1. March of Dimes. (2008). Low birthweight. http://www.marchofdimes.com/professionals/medicalresources_lowbirthweight.html

Why This Topic Is Important

Low birthweight babies are at increased risk of long-term disabilities, including mental retardation, chronic respiratory problems, cerebral palsy, childhood psychiatric disorders, hearing and vision impairments, autism, and death (1, 2). Women who are more likely to give birth to low birthweight babies include those with low incomes, inadequate prenatal care, smoking habits, and those under age 16 or over age 45 (1).

Babies born prematurely are at increased risk for newborn health complications (e.g., breathing problems), long-term physical and cognitive challenges (e.g., cerebral palsy, lung problems, mental retardation, learning and behavioral problems), and death (3). In fact, preterm birth is one of the leading causes of infant death in the U.S. (4). Most preterm babies require specialized care in a newborn intensive care unit (3). Women who are most likely to give birth preterm include those who have had a previous premature birth, those pregnant with twins, triplets, or more, and those with certain uterine abnormalities. In addition, demographic and behavioral factors can increase the risk of delivering preterm, including low socioeconomic status, being under age 17 or over age 35, inadequate prenatal care, and smoking during pregnancy (3). About 12% of all pregnancies in the U.S. result in preterm birth (4).

Sources for this narrative:

  1. March of Dimes. (2008). Low birthweight. http://www.marchofdimes.com/professionals/medicalresources_lowbirthweight.html
  2. Pinto-Martin, J. A., et al. (2011). Prevalence of Autism Spectrum Disorder in Adolescents Born Weighing <2000 Grams. Pediatrics, 2010-2846.
  3. March of Dimes. (2009-2010). Premature birth. http://www.marchofdimes.com/baby/premature_indepth.html
  4. Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health. (2010). Preterm labor and birth. http://www.nichd.nih.gov/health/topics/Preterm_Labor_and_Birth.cfm

Policy Implications

Some of the risk factors for low birthweight and preterm birth can be influenced by public and institutional policy focused on education, prevention, and treatment. These factors include smoking, drinking alcohol, or using illicit substances during pregnancy; being a teenage mother, and being overweight or underweight. Preterm births also can be medically induced or occur through elective cesarean sections, and they are more likely to occur when a mother gives birth to more than one baby at a time.

According to research and subject experts, policy options that could influence low birthweight and preterm births include:

  • Providing access to early and regular high-quality prenatal care (1)
  • Ensuring that health care systems train clinicians on identifying smokers among pregnant women, and that evidence-based tobacco cessation services are available to pregnant women and reimbursed by insurance (2, 3)
  • Sustaining adequate funding for universal screening for substance use among pregnant women, and for treatment services specifically designed for pregnant women who use alcohol or illicit drugs (4, 5)
  • Supporting public education and systems change to reduce the number of non-medically indicated induced preterm deliveries and cesareans (6, 7)
  • Promoting expanded research, education and demonstration projects aimed at reducing the rates of preterm labor and delivery (8)
  • Supporting a comprehensive approach to women’s health, including integration of reproductive planning into women’s routine health care, as good health before conception can improve pregnancy outcomes; included in this approach should be a focus on increasing interpregnancy intervals (at least 12 months), recognizing that short intervals are associated with increased risk for preterm birth (9, 10)

For more policy ideas and research on this topic, see kidsdata.org’s Research & Links section, or visit the March of Dimes. Also see Policy Implications on kidsdata.org under the Prenatal Care, Infant Mortality, Teen Births and Teen Sexual Health topics.

Sources for this narrative:

  1. March of Dimes. (2008). Low birthweight. http://www.marchofdimes.com/professionals/medicalresources_lowbirthweight.html
  2. Centers for Disease Control and Prevention. (2011). Tobacco use and pregnancy. Retrieved from: http://www.cdc.gov/reproductivehealth/TobaccoUsePregnancy/
  3. U.S. Department of Health and Human Services. (2008). Systems change: Treating tobacco use and dependence, based on the Public Health Service (PHS) clinical practice guideline—2008 update. Retrieved from: http://www.ahrq.gov/clinic/tobacco/systems.htm
  4. Chasnoff, I. J., McGourty, R. F., Wells, A. M., & McCurties, S. (2008). Perinatal substance use screening in California. NTI Upstream. Retrieved from: http://www.adp.cahwnet.gov/Alcohol/pdf/PerinatalSubstanceUseSR.pdf
  5. Brady, T. M., & Ashley, O. S. (2005). Women in substance abuse treatment: Results from the Alcohol and Drug Services Study (ADSS). US Department of Health and Human Services. Retrieved from: http://oas.samhsa.gov/WomenTX/WomenTX.htm#2.4
  6. March of Dimes. (2010). Elimination of non-medically indicated (elective) deliveries before 39 weeks gestational age. California Maternal Quality Care Collaborative, California Department of Public Health. Retrieved from:  http://www.cdph.ca.gov/programs/mcah/Documents/MCAH-EliminationOfNon-MedicallyIndicatedDeliveries.pdf
  7. Fleischman, A. R. (2010). What happens when babies are born too early? March of Dimes Foundation, Testimony before the US House of Representatives: Prematurity and Infant Mortality. Retrieved from: http://www.modimes.org/advocacy/prevention_indepth.html
  8. U.S. Department of Health and Human Services, Office of Adolescent Health. (2010). Programs for replication. Retrieved from: http://www.hhs.gov/ash/oah/oah-initiatives/tpp/programs.html
  9. DeFranco et al. (2007, September). A short interprenancy interval is a risk factor for preterm birth and its recurrence. American Journal of Obstetrics and Gynecology, (197)3. http://www.ajog.org/article/S0002-9378%2807%2900818-6/abstract
  10. Wise, P. (2008, November). Transforming Preconceptional, Prenatal, and Interconceptional Care Into A Comprehensive Commitment To Women's Health. Women’s Health Issues, (18)6, Supplement, S13-S18. http://www.whijournal.com/article/S1049-3867%2808%2900109-6/fulltext#sec4

How Children Are Faring

The percentage of California babies born at low birthweight increased from 6.1% in 1995 to 6.9% in 2005, and has remained fairly steady since then. County-level figures vary widely, from 4.4% to 7.4% in 2009. That year, the state and all counties with available data met the national Healthy People 2020 objective of no more than 7.8% of infants with low birthweight. In 2009, as in recent years, African American/Black mothers in California had a higher percentage of infants at low birthweight than mothers from other racial/ethnic groups. As for differences by age of mother, those age 45 and above consistently have the highest percentage of low birthweight babies in California.

California babies born at a very low birthweight remained at 1.1% or 1.2% from 1995 through 2009. The state and all but one county with available data in 2009 met the Healthy People 2020 objective of no more than 1.4% of infants with very low birthweight.

In 2009, 10.4% of infants were born preterm, which represents a decline from the high of 11.2% in 2005. As with low birthweight rates, county-level figures vary widely, from 5.8% to 13.5% of infants born preterm in 2009. Among counties with available data, all but six met the Healthy People 2020 objective of no more than 11.4% of infants born prematurely.

Research and Links

Websites with Related Information

Key Reports

County/Regional Reports