The Iowa HHS Vital Records program records around 40,000 births in the state annually. The health and social environments in which these births occur can impact health and development across the lifespan.
While most women have a normal term pregnancy and deliver a healthy infant, a safe and healthy pregnancy is not experienced by all women. Genetic, behavioral, social and environmental factors can affect reproduction and birth, from pre-conception to the post-partum period. The influence and interaction of these factors is complex, and there is still much we do not know.
This section provides an overview of births in Iowa, including outcomes that can be influenced by social and environmental factors. In order to better understand the role that environmental exposures play in reproductive and infant health problems, the Tracking Network collects and displays data on reproductive and birth outcomes including fertility and infertility, premature birth, infant deaths, birth weight, and sex ratio. Iowa Public Health Tracking has added additional data to provide a more complete picture of reproduction and births in Iowa.
The Tracking Network uses vital records data collected by the Iowa HHS Bureau of Health Statistics. Vital records are information about human life such as births and deaths.
The numbers and rates of prematurity, low birth weight, infant mortality and sex ratio 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.
To inform the public about adverse reproductive and birth outcomes.
For program planning and evaluation by state and local partners.
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.
Birth and death certificates and fetal death reports filed with the Iowa Department of Health and Human Services 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.
The Iowa Public Health Tracking portal displays reproductive and birth outcome data from the year 2000 through the most recent year of data available.
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 include all infant deaths occurring in 2010 that have been linked to their corresponding birth certificates, whether the birth occurred in 2009 or in 2010.
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.
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 perinatal 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.
Our understanding of risk factors for reproductive problems such as infertility, low birth weight, prematurity and fetal and infant death has increased over the past decades. Certain health conditions, social and economic factors and behaviors can increase the risk of adverse reproductive and birth outcomes. We have also learned that environmental exposures can play a role in reproductive and birth outcomes. However, there is still much we do not know.
Exposure and Risk
The following are some of the possible environmental exposure and risk factors that are associated with reproductive and birth outcomes:
Exposure of nonsmoking pregnant women to environmental tobacco smoke (also known as secondhand smoke) may be a risk factor for preterm birth, low birth weight and possibly fetal death or miscarriage.
Exposure to air pollution may be related to both low birth weight and preterm birth, even at low levels.
A pregnant woman's exposure to lead may cause preterm birth, low birth weight and spontaneous fetal death or miscarriage.
Some pesticides have been linked in human studies with problems including miscarriages, birth defects and learning or developmental disabilities in children.
Although age and certain health conditions are more commonly associated with infertility, it is believed that environmental contaminants may cause infertility by creating other health conditions. For example, some research suggests that environmental contaminants can affect a woman's menstruation and ovulation. Low-level exposures to compounds such as phthalates, polychlorinated biphenyls (PCBs), dioxin and pesticides are suspected risk factors. Much more research needs to be done to find out how environmental contaminants may be affecting human fertility.
Some studies have suggested that environmental hazards can affect how many males are born. Parents and the fetus can be exposed to different hazards referred to as endocrine disruptors. Fewer males are conceived when exposure to endocrine disruptors causes a decrease in testosterone. Diethylstilbestrol (DES), a synthetic estrogen widely prescribed to pregnant women during the mid-1900s, is a strong endocrine disruptor. Previous studies have suggested an association between endocrine-disrupting compounds and the secondary sex ratio (the sex ratio of the grandchildren of the exposed women). Several studies show that declines in the sex ratio of males to females at birth may be associated with occupational exposure, or exposure to air pollution.
Prevention
Women who are pregnant or may become pregnant should follow their doctor's advice on how they can have a healthy baby. Doctors can also answer questions on fertility and give advice on conceiving. Early and regular prenatal care helps identify conditions and behaviors that can result in adverse reproductive and birth outcomes.
Here are some ways to prevent environmental exposures:
Stop smoking and avoid secondhand smoke.
Limit outdoor activity when the Air Quality Index (available on the EPA AirNow website) shows unhealthy levels of air pollutants.
Cut out or reduce any indoor sources of particulate matter, like wood-burning stoves and fireplaces, and try to reduce the amount of time spent outdoors near areas with higher levels of air pollution, such as areas with a lot of traffic.
Stay away from lead.
Stay away from mercury. Some fish, especially albacore tuna, may be contaminated with mercury.
Do not use pesticides if you are pregnant. Stay away from rooms that have been recently sprayed with insecticides and from other areas with potential pesticide exposure.
