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Massachusetts Department of Public Health seal Massachusetts Environmental Public Health Tracking

Low Birth Weight (Growth Retardation)

Baby hand laying on top of mother's hand
Did You Know?

Massachusetts is ranked 20th in percent of babies born at low birth weight.

Source: Children's Defense Fund 2013

Low birth weight occurs when the growth of the fetus is abnormally slow. Growth retardation is measured by the number and percentage of term, singleton infants with low and very low birth weights. Low birth weight is when an infant is born with a weight less than 2,500 grams, or 5.5 pounds at birth. Very low birth weight is when an infant is born with a weight less than 1,500 grams, or 3.3 pounds at birth.

Compared to normal birth weight infants, low birth weight infants may be more at risk for:

  • Illness through the first six days of life
  • Infections
  • Long-term impairment, such as delayed motor and social development or learning disabilities

Exposures to lead, solvents, pesticides, and polycyclic aromatic hydrocarbons (PAHs) during pregnancy have been associated with low birth weight infants. Non-environmental risk factors include exposure to cigarette smoking (from mothers who smoke or from second-hand smoke) and no or late prenatal care.

Data Considerations

When reviewing and interpreting low birth weight data, it is important to take into consideration the following:

  • The low birth weight counts and percentages for EPHT are based on term, singleton live births only. Proportions of low birth weight births among live multiple birth categories may also be informative measures, particularly since plural births are a risk factor for prematurity, but are not considered in the EPHT measures.
  • There may be uncertainties associated with gestational age estimates due to imperfect maternal recall or misidentification of the last normal menstrual period due to post conception bleeding and/or delayed ovulation.
  • Increased low birth weight counts and percentages do not necessarily mean that environmental exposures are the cause.
  • The data presented are based on the location of the residence at the time of birth or death. The place of residence or potential exposure during gestation or at the time of conception, when an exposure that may have affected the outcome could have occurred, may be different.

For additional information, please read the FAQ

Available Data on Low Birth Weight

Use the Explore Maps & Tables link on this page to access the following measures for low birth weight in your community. The most current available data will be shown. Be sure to check the site periodically as new data is added each year. To protect privacy, no information is shown that could identify an individual.

  • Annual number and percent of low birth weight (less than 2,500 grams) term, singleton live births by community, county, and state
  • Average annual number and percent of very low birth weight (less than 1,500 grams) term, singleton live births by community, county, and state

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