About Reproduction and Birth Data
The Tracking Network uses vital records data collected by the Bureau of Health Statistics. Vital records are information about human life such as births and deaths.
This page provides general information about the reproductive and birth outcomes data and measures developed by the Iowa Public Health Tracking program. Contact Us for more information about these data.
Information on this page:
What do these data tell us?
- The numbers and rates of prematurity, low birth weight, , and in Iowa by year and race/ethnicity.
- Race is displayed using three race groups: 'Black', 'White', and 'Other'. The 'Other' group includes the bridged-race categories of 'American Indian/Alaskan Native', 'Asian or Pacific Islander', and 'Unknown'.
- If certain reproductive and birth outcomes or sex ratio are going up or down over time.
- If a segment of a population is at increased risk for adverse reproductive or birth outcomes.
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How can we use these data?
- To inform the public about adverse reproductive and birth outcomes.
- For program planning and evaluation by state and local partners.
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What can these data not tell us?
- The causes of reproductive and birth outcomes.
- Environmental exposure-related causes of adverse reproductive and birth outcomes are only one piece of a puzzle that includes many other factors such as access to and quality of health care, maternal characteristics, genetic factors, behavioral factors, childcare skills, and injury prevention. Many of these factors are not included in birth or death records. Variables that are included are often difficult to interpret without additional information on social and behavioral factors.
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What is the source of the data?
- Birth and death certificates and fetal death filed with the Iowa Department of Public Health Vital Records program are the data sources for the reproductive and birth outcomes measures.
- Measures are computed using data on births to Iowa resident mothers, with residency determined by address at time of birth as listed on the birth certificate. Race and ethnicity categories for births are based on the race and ethnicity of the mother as reported on the birth certificate. Hispanic ethnicity includes anyone indicating they are of Hispanic/Latino descent regardless of race.
- The National Center for Health Statistics is the source for national numbers on these pages.
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What time period of data is available?
- The Iowa Public Health Tracking portal displays reproductive and birth outcome data from the year 2000 through the most recent year of data available.
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How are reproductive and birth outcomes identified?
- Reproductive and birth outcomes are identified from birth and death certificates and fetal death reports filed with the IDPH Vital Records.
- Preterm: Births occurring before 37 completed weeks are considered preterm.
- Low Birth Weight: Birth weight is the first weight of the newborn obtained after birth. Newborns with birth weights less than 2,500 grams are considered low birth weight.
- Infant Mortality: Refers to any death of a child before the age of 1 year. Mortality data are calculated using the period linked approach, where all infant deaths occurring in a given data year are linked to their corresponding birth certificates, whether the birth occurred in that year or the previous year. For example, the 2010 mortality data includes all infant deaths occurring in 2010 that have been linked to their corresponding birth certificates, whether the birth occurred in 2009 or in 2010.
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What is the difference between a number and rate? How would I use them?
Number:
- The number indicates the total number of reproductive and birth outcome.
- To understand the magnitude or what the overall burden is, use the number.
- If there are fewer than 5 cases, Iowa Public Health Tracking program suppresses those numbers to preserve data privacy.
Rate:
- A rate is a ratio between two measures with different units.
- In our analysis, a rate is calculated using the number of events as the numerator (the number of a reproductive and birth outcome during a period of time) divided by the number of live births during a period of time. This fraction is then multiplied by either 100 (percent) or 1,000 (per 1,000 live births) to provide a more recognizable value.
- To understand the probability or what the underlying risk in a population is, use a rate.
- To protect an individual's privacy, rates based on counts under 5 are suppressed.
- Rates have been rounded to the nearest tenth of a percent.
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What are the limitations of the data?
- The quality of vital statistics data is directly related to the completeness and accuracy of the information contained in the source documents.
- Estimates of the length of a pregnancy ("gestational age") were included in most Iowa birth records. The gestational age is determined by the best obstetric estimate of the infant's gestation in completed weeks based on all factors and assessments (such as ultrasound). This is a complex assessment, and not based on date of last menstrual period.
- Timeliness is a limitation of the vital records system. It is not unusual for a birth record to be amended weeks or months after it was originally processed due to adoption, correction, or out-of-state birth. Because of the time it takes to correct and amend birth records, the final birth file for a particular calendar year can take many months after the end of the calendar year to close and be made available for epidemiological use. Data on infant deaths takes even longer to be ready for analysis because of the time it takes to link birth and death files.
- Residential information is very important when examining environmental exposures and other risk factors that may occur before birth. A limitation of the data source is that the place of residence during pregnancy (and, with infant death, residence during first year of life) may not be represented by maternal residence at time of birth (or death). Adoption replaces demographic characteristics of the birth mother (including mother's race/ethnicity, education level, etc.) with those of the adoptive mother. Replacement of birth mother address with adoptive mother address further biases the place of residence data element.
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Where can I find more technical information about the data?
More detailed documentation of the reproductive and birth outcome data can be found in the following documents:
Indicator Profiles
Infant Mortality 
Low Birth Weight
Premature Birth
Sex Ratio
Total Fertility Rate
Descriptive Metadata
Reproductive and Birth Outcomes
Contact Us to learn more about reproductive and birth outcome data, or any of the measures displayed on the Iowa Public Health Tracking Portal.
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