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Massachusetts Department of Public Health seal Massachusetts Environmental Public Health Tracking

Premature Births

A premature birth occurs when an infant is born at least 3 weeks before the scheduled due date. Data for premature births are reported by the number and percentage of premature births (born before completing 37 weeks of gestation) and very premature births (born before completing 32 weeks of gestation).

Being born prematurely is the leading cause of death among infants. It is also a leading cause of infant illnesses, diseases, and long-term disabilities including:

Did You Know?
The percentage of premature births rose significantly in the United States and Massachusetts between 1990 and 2006 but has been declining since then; likely due to reduced use of "elective" procedures, such as induced labor and caesarian delivery. Source: National Vital Statistics Report volume 61, number 1 2012
  • Mental retardation
  • Cerebral palsy
  • Breathing and respiratory problems (premature lung development)
  • Feeding and digestive problems (including birth defects such as gastroschisis)
  • Vision and hearing loss

Three groups of women are at greatest risk of premature birth:

  • Women who have had a previous premature birth
  • Women who are pregnant with twins, triplets, or more
  • Women with certain uterine or cervical abnormalities

Exposures during pregnancy to air pollution or lead and some solvents in drinking water have been related to an increase risk of giving birth to a baby prematurely. For a list of all known risk factors for premature birth, please click the FAQ link at the top of the page.

Data Considerations

When reviewing and interpreting data on premature births, it is important to take into consideration the following:

  • The premature birth counts and percentages for EPHT are based on live singleton births only. Proportions of premature births among live multiple birth categories may also be informative measures, particularly since plural births are a risk factor, 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 premature birth counts and percentages do not necessarily mean that environmental exposures are the cause. Environmental exposures may be one of several reasons for a premature or low birth weight birth.
  • Premature birth counts and percentages may be affected by a number of factors. For example, when a fetus is terminated prior to 37 weeks gestation that otherwise could have resulted in a live birth, the rate of premature birth decreases. Conversely, when an induced termination does not occur, a premature birth may be gained and the percentage increases. Therefore, low premature birth counts and percentages could indicate high fetal mortality and poor reproductive health of a population or a high abortion rate, whereas high premature birth counts and percentages could be a result of advanced technology and life-saving techniques.
  • 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 Premature Births

Use the Explore Maps & Tables link on this page to access the following measures for premature births in your community. The most current available data will be shown. Be sure to check the site periodically as new data are added each year.

To protect privacy, no information is shown that could identify an individual.

  • Annual number and percent of premature (less than 37 complete weeks gestation) live singleton births by county and statewide
  • Average annual number and percent of very premature (less than 32 complete weeks gestation) live singleton births by county and statewide over 5 year period
More About the Data

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