Environmental Public Health Tracking: Birth Outcomes Data

Reproduction is complex, and many factors affect the 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.

Reproductive outcomes, also called birth outcomes, refer to how a baby is conceived, carried to term, and delivered.

The Wisconsin Tracking Program hosts data on six types of reproductive outcomes:

Access the birth outcomes data

 

An adult holds her baby while the doctor gives her a vaccination

Interested in environmental health data?

Join the environmental health listserv by sending an email to DHS Environmental Public Health Tracking with the subject line "Join envhealth listserv."

 

Frequently asked questions

In the section below, there are frequently asked questions about reproductive outcomes in general. On each specific outcome’s page, there are frequently asked questions about that type of reproductive outcome.

What is reproductive health?

Reproductive health refers to health status of reproductive processes, functions, and systems. Reproductive health includes the diseases, disorders, and conditions that affect the functioning of the male and female reproductive systems during reproductive age.

Reproductive health is influenced by many factors, including:

  • Age
  • Genetics
  • Medical history/overall health
  • Income/education level
  • Health behaviors
  • Access to medical care
  • Environmental exposures

What are birth outcomes?

Reproductive outcomes, also called reproductive health outcomes or birth outcomes, include disorders that happen as a result of poor reproductive health including birth defects, developmental disorders, fetal growth restriction, low birth weight, preterm birth, reduced fertility/infertility, impotence, and menstrual disorders.

How are birth outcomes related to the environment?

Wisconsin Tracking hosts data on various measures of birth outcomes and infant deaths to explore changes in reproductive health outcomes over time and place. Studying these trends may provide clues about how environmental factors affect reproductive health.

Reproduction is a complex process. Exposure to chemicals in the environment can affect the ability to have babies. These exposures can also affect proper growth and development of babies before and after they are born.

Environmental toxins may be especially harmful to babies while they are still in their mother’s uterus. For example, mercury exposure can cause birth defects and brain disorders in babies born to mothers who eat large amounts of mercury-rich fish. While the effects of some environmental exposures are known, many questions remain unanswered.

Both the male and female reproductive systems play a role in pregnancy. Problems with these systems can affect fertility and the ability to have children. Reproductive problems occur in both men and women. Learn more about reproductive health on the Centers for Disease Control and Prevention's (CDC) Reproductive Health page.

What is the data source?

Wisconsin Tracking hosts data from the statistical resident birth and death files, maintained by the Wisconsin Vital Records Office of the Office of Health Informatics (OHI) at the Wisconsin Department of Health Services. OHI also provides reproductive outcomes data on the Wisconsin Interactive Statistics on Health (WISH) database and in statistical reports.

Which measures does Wisconsin Tracking have for birth outcomes?

There are several terms in this section related to birth, like post-neonatal, low birth weight, etc. Consult the glossary of terms for definitions of these terms.

Note: the term “singleton” refers to singly born babies. In other words, singleton babies were not part of a set of twins, triplets, etc.

  • Prematurity
    • Annual percent of singleton premature babies, by county, gender, age, and race
    • Annual count of singleton premature babies, by county, gender, age, and race
    • Annual percent of singleton very premature babies, by county, gender, age, and race
    • Annual count of singleton very premature babies, by count, gender, age, and race
  • Low birth weight
    • Annual percent of low birth weight babies, by gender, age, and race
    • Annual percent of singleton low birth weight babies, by gender, age, and race
    • Annual percent of low birth weight babies by county
    • Annual percent of singleton low birth weight babies by county
  • Birth rate
    • Annual birth rate per 1,000 babies, by county, gender, age, and race
    • Annual singleton birth count, by county, gender, age, and race
    • Annual singleton birth rate per 1,000 babies, by county, gender, age, and race
    • Annual total birth count, by county, gender, age, and race
  • Infant mortality
    • Annual infant mortality rate per 1,000 babies, by county, gender, age, and race
    • Annual perinatal mortality rate per 1,000 babies by county
    • Annual perinatal mortality counts by county
    • Multi-year neonatal mortality rate per 1,000 babies, by county, gender, age, and race
    • Multi-year neonatal mortality count of babies, by county, gender, age, and race
    • Annual neonatal mortality rate per 1,000 babies by county
    • Annual neonatal mortality count of babies by county
    • Multi-year post-neonatal mortality rate per 1,000 babies, by county, gender, age, and race
    • Multi-year post-neonatal mortality count of babies, by county, gender, age, and race
  • Fertility and infertility
    • Annual total fertility rate by county
  • Sex ratio
    • Annual singleton sex ratio by county

What are some considerations for interpreting the data?

  • Wisconsin Vital Records has cooperative exchange procedures in place to get data on Wisconsin residents born in other states. However, it is possible not all other states have provided complete information at the time the report was created. The numbers are likely quite small and probably have limited impact on the measures provided from the portal.
  • The measures are based on responses recorded on birth certificates.
  • Data users should keep in mind that many factors contribute to a disease. These factors should be considered when interpreting the data. Factors include:
    • Demographics (race, gender, age)
    • Socioeconomic status (income level, education)
    • Geography (rural, urban)
    • Changes in the medical field (diagnosis patterns, reporting requirements)
    • Individual behavior (diet, smoking)

Where can I learn more about reproductive outcomes?

Birth outcomes data details

Data details

Fertility

Total fertility rate per 1,000 women of reproductive age

These data are collected from birth certificates and are provided by the CDC's National Center for Health Statistics Vital Statistics System. This measure is an estimate of the average number of children a hypothetical cohort of 1,000 women would birth if the age-specific birth rates were observed in a given year. It is calculated by multiplying the sum of these age-specific fertility rates by five. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases or events per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than ten cases or events.

Infant mortality

Average annual number of infant deaths

These data are collected from linked birth and death certificate data provided by the CDC's National Center for Health Statistics. This measure is a count of deaths which occurred in infants younger than one year of age; the presented data are averages over a five year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases. Please note that counts are a statistically limited way to consider deaths because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more deaths simply because they have more people. A rate is a better measure for true comparison between counties.

Average annual number of neonatal deaths

These data are collected from linked birth and death certificates provided by the CDC's National Center for Health Statistics. This measure is a count of deaths which occurred in infants younger than 28 days old; the presented data are averages over a five-year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases. Please note that counts are a statistically limited way to consider deaths because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more deaths simply because they have more people. A rate is a better measure for true comparison between counties.

Average annual number of perinatal deaths

These data are collected from linked birth and death certificate data provided by the CDC's National Center for Health Statistics. This measure is a count of deaths which occurred in fetuses and infants from between 28 days of gestation to seven days after birth; the presented data are averages over a five-year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases. Please note that counts are a statistically limited way to consider deaths because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more deaths simply because they have more people. A rate is a better measure for true comparison between counties.

Average annual number of postneonatal deaths

These data are collected from linked birth and death certificate data provided by the CDC's National Center for Health Statistics. This measure is a count of deaths which occurred in infants 28 days to less than one year of age; the presented data are averages over a five-year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases. Please note that counts are a statistically limited way to consider deaths because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more deaths simply because they have more people. A rate is a better measure for true comparison between counties.

Infant mortality rate per 1,000 live births

These data are collected from linked birth and death certificate data provided by the CDC's National Center for Health Statistics. This measure includes the number of deaths which occurred in infants younger than one year of age divided by all live births; the presented data are averages over a five-year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Neonatal mortality rate per 1,000 live births

These data are collected from linked birth and death certificate data provided by the CDC's National Center for Health Statistics. This measure includes the number of deaths which occurred in infants younger than 28 days old divided by all live births; the presented data are averages over a five-year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Perinatal mortality rate per 1,000 live births

These data are collected from linked birth and death certificate data provided by the CDC's National Center for Health Statistics. This measure includes the number of deaths which occurred in fetuses and infants from between 28 weeks of gestation to seven days after birth; the presented data are averages over a five-year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Postneonatal mortality rate per 1,000 live births

These data are collected from linked birth and death certificate data provided by the CDC's National Center for Health Statistics. This measure includes the number of deaths which occurred in infants 28 days to less than one year of age divided by all live births; the presented data are averages over a five-year time period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Low birthweight (<2,500 Grams)

Number of live term singleton births (counts)

These data are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure is a count of live singleton births at term (≤ 37 weeks of gestation) with a birthweight less than 2,500 grams. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases or events. Please note that counts are a statistically limited way to consider low birthweight outcomes because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more cases simply because they have more people. A rate is a better measure for true comparison between counties.

Percent of live term singleton births

These data are are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure includes the number of live singleton births at term (≤ 37 weeks of gestation) with a birthweight less than 2,500 grams divided by the total number of live singleton births. Low birthweight is expressed as a percentage of all live births. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Preterm (37 weeks gestation)

Number of live singleton births (counts)

These data are collected from birth certificates provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure is a count of live singleton births before 37 weeks of gestation. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases. Please note that counts are a statistically limited way to consider prematurity because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more deaths simply because they have more people. A rate is a better measure for true comparison between counties.

Percent of live singleton births

These data are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure includes the number of live singleton births before 37 weeks of gestation divided by the total number of live singleton births. Prematurity is expressed as a percentage of all live births. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Sex ratio

Male to female sex ratio at birth (term singleton only)

These data are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure is calculated by dividing male births by female births; only live singleton term (≤ 37 weeks of gestation) births are included. A rate of 1.000 indicates that an equal number of male and female infants were born in a given year.

Very low birthweight (<1,500 grams)

Average annual number of live singleton births

These data are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure is a count of live singleton births at term (≤ 37 weeks of gestation) with a birthweight less than 1,500 grams. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. This measure is presented as an average over a five-year period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases. Please note that counts are a statistically limited way to consider low birthweight outcomes because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more cases simply because they have more people. A rate is a better measure for true comparison between counties.

Average annual percent of live singleton births

These data are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure includes the number of live singleton births at term (≤ 37 weeks of gestation) with a birthweight less than 1,500 grams divided by the total number of singleton infants live born. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. This is expressed as an average percentage over a five-year period. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Very preterm (<32 weeks gestation)

Average annual number of live singleton births

These data are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure is a count of live singleton births before 32 weeks of gestation; it is presented as an annual average over a five-year period. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases. Please note that counts are a statistically limited way to consider prematurity because they do not allow for accurate comparison between counties. Counties with higher populations, such as Milwaukee, will have more cases simply because they have more people. A rate is a better measure for true comparisons between counties.

Average annual percent of live singleton births

These data are collected from birth certificates and provided by the CDC's National Center for Health Statistics National Vital Statistics System. This measure includes the number of live singleton births before 32 weeks of gestation divided by the total number of live singleton births. It is expressed as a percentage of all live births. Gestational age is determined by an algorithm that uses the clinician's estimate of gestational age and the mother's last reported normal menses. Prior to 2008, the National Environmental Public Health Tracking Network suppressed data for counties with fewer than six cases per 100,000 to protect confidentiality. However, counties with zero cases were not suppressed. Since 2008, data has been suppressed for all counties with fewer than 10 cases.

Glossary and definitions of terms

Explore definitions and explanations of terminology found on the portal, like age-adjusted rate and confidence intervals.

Last Revised: August 2, 2022