Environmental Public Health Tracking: Low Birth Weight Data

Reproduction is complex, and many factors affect parents’ ability to make a baby, carry the baby to term, and deliver the baby without complications.  These factors include age, genetics, income/education level, and many others.

Low birth weight is one type of birth outcome.  Review the FAQs below for more information about low birth weight.

Access birth outcomes data

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What is low birth weight?

A baby is born with a low birth weight when s/he weighs less than 5 pounds, 8 ounces.

What is very low birth weight?

A baby is born with a very low birth weight when s/he weighs less than 3 pounds, 4 ounces.

What are the risk factors for low birth weight?

Several risk factors increase a pregnant woman’s chances of having a low birth weight baby:

  • Smoking
  • Drinking alcohol
  • Lack of weight gain
  • Younger than 15 years old or older than 35 years old
  • Low socioeconomic status (low income, education level)
  • Previous preterm birth
  • Exposure to air pollution
  • Drinking water contaminated with lead

Is low birth weight preventable?

Early and continuous prenatal care helps identify conditions and behaviors that can result in low birth weight babies.  Women should avoid exposure to risk factors (listed above) and talk to their doctors before becoming pregnant.  Learn more about prevention on the CDC's Reproductive and Birth Outcomes: Low Birth Weight page.

What is the relationship between low birth weight and the environment?

Low birth weight has been linked to exposure during pregnancy to lead, solvents, pesticides, and polycyclic aromatic hydrocarbons, which are a group of over 100 contaminants produced by burning fuels like coal.  A low birth weight birth can occur from slow fetal growth over a full-term pregnancy, being born premature, or both. These conditions often have separate causes. 

Where can I learn more about low birth weight?

Last Revised: April 2, 2020