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Last Edited: 9/30/2010

Prematurity and Growth Retardation

Prematurity and growth retardation are commonly used measures of maternal and infant health.  Prematurity occurs when a baby is born too early.  Growth retardation occurs when a fetus grows insufficiently while in the womb.  Both conditions are preventable to varying degrees, and both conditions have been found to be influenced by environmental hazards.

What are prematurity and growth retardation?

Prematurity is when an infant is born early.  Preterm birth rate is a measure of prematurity.  Infants are considered preterm when they are born before completing 37 weeks (about 8.5 months) of pregnancy.

Growth retardation is when an infant fails to grow sufficiently during pregnancy.  This measurement is slightly more complicated than that for prematurity.  Infants are considered to have low birthweight if they weigh less than 2,500 grams (about 5.5 pounds) at birth.  Most low birthweight infants are small because they were born preterm and did not have enough time to finish growing before birth.  Therefore, infants classified as “preterm” and infants classified as “low birthweight” are often the same newborns.  Frequently, however, we wish to consider infants with low birthweight born at full term, which is sometimes called “small-for-gestational age”. 

One way to look at growth retardation is to count the number of full term infants that have low birthweights in spite of being full term.  This means that the baby had enough time in utero, but was still small when born.  An infant that weighs less than 2,500 grams but has completed 37 or more weeks of pregnancy is considered to have term low birthweight. 

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What are the health consequences of prematurity and growth retardation?

Infants that are born preterm or with a low birthweight are at higher risk of dying in the first year of life and of having developmental problems throughout life.1-6 Overall, approximately one-third of all infant deaths in the US are associated with prematurity.7

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What causes prematurity and growth retardation?

Many factors can influence prematurity and fetal growth.  Numerically, most of the infants born with low birthweight are ones that are delivered preterm. Established factors related to prematurity and growth retardation include:

  • Maternal smoking
  • Nutritional status
  • Medical care
  • Levels of stress and/or social support

Scientists are now learning that exposure to pollution during pregnancy can also have an effect on prematurity and growth impairment.8-23 Preterm birth may occur spontaneously or may be medically induced in the situation of impending fetal or maternal compromise.  Rates of preterm birth are therefore partly influenced by obstetrical practice patterns, although fetal and maternal distress and spontaneous preterm birth may have common sources. 24, 25

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1. Barker D, Osmond C. Infant Mortality, Childhood Nutrition, and Ischaemic Heart Disease in England and Wales. Lancet. 1986;1:1077-1081.
2. Barker D, Osmond C, Golding J, Kuh D, Wadsworth M. Growth in utero, blood pressure in childhood and adult life, and mortality from cardiovascular disease. British Medical Journal. 1989;298:564-567.
3. Hack M, Klein N, Taylor H. Long-term developmental outcomes of low birthweight children. Future Child. 1995;5:176-193.
4. McCormick M. The Contribution of Low Birth Weight to Infant Mortality and Childhood Morbidity. New England Journal of Medicine. 1985;312:82-90.
5. Overpeck MD, Moss A, Hoffman H, Hendershot G. A Comparison of the Childhood Health Status of Normal Birth Weight and Low Birth Weight Children. American Journal of Public Health. 1989;104:58-70.
6. Li C, Daling J, Emanuel I. Birthweight and risk of overall and cause-specific childhood mortality. Paediatric and Perinatal Epidemiology. 2003;17:164-170.
7. MacDorman M, Callaghan W, Mathews T, Hoyert D, Kochanek K. Trends in preterm-related infant mortality by race and ethnicity, United States, 1999-2004. International Journal of Health Services. 2007;37(4):635-641.
8. Berry M, Bove F. Birth Weight Reduction Associated with Residence near a Hazardous Waste Landfill. Environmental Health Perspectives. 1997;105:856-861.
9. Bobak M. Outdoor Air Pollution, Low Birthweight, and Prematurity. Environmental Health Perspectives. 2000;108:173-176.
10. Dejmek J, Selevan S, Benes I, Solansky I, Sram R. Fetal Growth and Maternal Exposure to Particulate Matter During Pregnancy. Environmental Health Perspectives. 1999;107:475-480.
11. Dejmek J, Solansky I, Benes I, Lenicek J, Sram R. The impact of polycyclic aromatic hydrocarbons and fine particles on pregnancy outcome. Environmental Health Perspectives. 2000;108:1159-1164.
12. Jedrychowski W, Brendkowska I, Flak E, et al. Estimating risk for altered fetal growth resulting from exposure to fine particles during pregnancy: An epidemiologic prospective cohort study in Poland. Environmental Health Perspectives. 2004;112:1398-1402.
13. Lin S, Hwang S-A, Marshall E, Marion D. Does Paternal Occupational Lead Exposure Increase the Risks of Low Birth Weight or Prematurity. American Journal of Epidemiology. 1998;148(2):173-181.
14. Liu S, Krewski D, Shi Y, Chen Y, Burnett R. Association between gaseous ambient air pollutants and adverse pregnancy outcomes in Vancouver, Canada. Environmental Health Perspectives. 2003;111:1773-1778.
15. Longnecker M, Klebanoff M, Zhou H, Brock J. Association between Maternal Serum Concentration of the DDT Metabolite DDE and Preterm and Small-for-gestational-age Babies at Birth. Lancet. 2001;358:110-114.
16. Nieuwenhuijsen M, Toledano M, Eaton N, Fawell J, Elliott P. Chlorination Disinfection Byproducts in Water and their Association with Adverse Reproductive Outcomes: A Review. Occupational and Environmental Medicine. 2000;57:73-85.
17. Patandin S, Koopman-Essenboom C, De Ridder M, Weisglas-Kuperus N, Sauer P. Effects of Environmental Exposure to Polychlorinated Biphyenyls and Dioxins on Birth Size and Growth in Dutch Children. Pediatric Research. 1998;44(4):538-545.
18. Perera F, Raugh V, Whyatt R, et al. Molecular evidence of an interaction between prenatal environmental exposures and birth outcomes in a multiethnic population. Environmental Health Perspectives. 2004;112:626-630.
19. Perera F, Rauh V, Tsai W, et al. Effects of transplacental exposure to environmental pollutants on birth outcomes in a multiethnic population. Environmental Health Perspectives. 2003;111:201-205.
20. Ponce N, Hoggatt K, Wilhelm M, Ritz B. Preterm birth: The interaction of traffic-related air pollution with economic hardship in Los Angeles. American Journal of Epidemiology. 2005;162:140-148.
21. Ritz B, Yu F. The Effect of Ambient Carbon Monoxide on Low Birth Weight Among Children Born in Southern California Between 1989 and 1993. Environmental Health Perspectives. 1999;107:17-25.
22. Rylander L, Stromberg U, Dyremark E, Ostman C, Nilsson-Ehle P, Hagmar L. Polychlorinated Biphenyl in Blood Plasma among Swedish Female Fish Consumers in Relation to Low Birthweight. American Journal of Epidemiology. 1998;147(5):493-502.
23. Wang X, Ding H, Ryan L, Xu X. Association Between Air Pollution and Low Birth Weight: A Community-based Study. Environmental Health Perspectives. 1997;105:514-520.
24. Ananth C, Joseph K, Oyelese Y, Demissie K, Vintzileos A. Trends in preterm birth and perinatal mortality among singletons: United States, 1989 through 2000. Obstetrics and Gynecology. 2005;105:1084-1091.
25. Ananth C, Vintzileos A. Epidemiology of preterm birth and its clinical subtypes. Journal of Maternal-Fetal and Neonatal Medicine. 2006;19(12):773-782.