Remedial effectiveness of a pond biomanipulation: Habitat value and concentrations of polychlorinated biphenyls in fish

The fish and plant communities in a pond contaminated with polychlorinated biphenyls (PCBs) in East Tennessee, USA, were manipulated to reduce ecological and human-health risk associated with exposure to the chemical contaminants. We evaluated the success of the remedial action using a habitat valuation approach, as well as measuring PCB concentrations in fish. Risk reduction objectives included: alter the fish community to favor fish that do not resuspend, bioaccumulate, or biomagnify PCBs; stabilize contaminated sediments to improve water quality; and stabilize shoreline soils and enhance riparian habitat. Fish targeted for removal included gizzard shad, largemouth bass, and nonnative carp. Reduced PCB concentrations in fish have characterized the new bluegill-dominated community, although a weir-overtopping event led to the need for additional removals of gizzard shad and largemouth bass. Sunfish abundance is high, as was intended. Moreover, amphibian and waterbird diversities have increased in the years following biomanipulation, possibly owing to improvements in the riparian zone and increased structural (vegetation) complexity in both the aquatic and terrestrial environment. Thus, the remedial action has improved aspects of habitat value, and PCB concentrations in sunfish have dropped below the remediation level (risk-based target value) for this pond (1 µg/g in fish fillets or 2.3 µg/g in whole body fish).

Variation in natural attenuation rates of polychlorinated biphenyls (PCBs) in fish from streams and reservoirs in East Tennessee observed over a 35-year period

Environmental contamination due to human activities is a major concern, particularly for persistent chemicals. Within catchments, persistent chemicals linked to negative health outcomes such as polychlorinated biphenyls (PCBs) have great potential to be transported, through adsorption or biological uptake, with downstream locations acting as sinks for accumulation. Here we present long-term trends in PCB bioaccumulation in fish found in lower-order tributaries on the Oak Ridge Reservation, an impacted US Department of Energy property in East Tennessee, USA, and a large reservoir system adjacent to it composed of parts of the Clinch and Tennessee Rivers. Given that the reservoir system has experienced no direct PCB mitigation activities, this record offers an opportunity to explore potential natural attenuation of PCBs within a large lotic ecosystem. Attenuation rates ranged from 0% to 8% yr^-1 in minnows and sunfish at stream sites and 5.4-11.3% yr^-1 in catfish at reservoir sites. These rates are comparable to findings from similar studies in other regions, suggesting a consistency in responses since the banning of PCB production in 1979. Further, results suggest that PCB sources from discharge outfalls are important locally but are not primarily responsible for sustaining PCB contamination in downstream reservoirs.

Stannous chloride as a tool for mercury stripping in contaminated streams: Experimental assessment of toxicity in an invertebrate model species

The chronic toxicity of an innovative Hg water treatment system using tin (Sn) (II) chloride (SnCl₂) followed by air stripping was assessed through measurements of survival, growth, and reproduction rate in the freshwater cladoceran Ceriodaphnia dubia, a model species for toxicity testing. We first calculated the concentrations of Hg causing 25% reduction in survival and reproduction (Lethal or Inhibition Concentrations, or LC₂₅ and IC₂₅, for survival and reproduction, respectively) through exposure to aqueous Hg at concentrations ranging from 0 to 25,000 ng L^-1. Then, we treated media (DMW and natural stream water) contaminated with Hg at LC₂₅ and IC₂₅ concentrations with SnCl₂ at a Sn:Hg stoichiometric ratio of 8:1 and air stripping and exposed C. dubia to this Sn-amended media. Our results showed that Hg significantly affected survival, reproduction rates and impaired growth. SnCl₂-treatment removed 100% of the Hg from the media at all concentrations tested with no deleterious effects on survival, growth and reproduction. Our results confirmed the efficacy of SnCl₂ in removing aqueous Hg from stream water and showed that the added Sn did not impact C. dubia at the concentrations tested, supporting the suitability of SnCl₂-based treatments in appropriate Hg-contaminated environments.

Comparing Trace Element Bioaccumulation and Depuration in Snails and Mayfly Nymphs at a Coal Ash-Contaminated Site

We examined the bioaccumulation of essential (Cu, Fe, Se, and Zn) and nonessential (As and Hg) trace elements in 2 aquatic invertebrate species (adult snails and mayfly nymphs) with different feeding habits at the site of a coal ash spill. Differences in food web pathway, exposure concentrations, and biological processing affected bioaccumulation patterns in these species. Mayflies had higher body burdens, but snails had higher retention of most elements studied. Environ Toxicol Chem 2020;39:2437-2449. © 2020 SETAC.

The Effect of Dietary Exposure to Coal Ash Contaminants within Food Ration on Growth and Reproduction in Daphnia magna

Coal ash contains numerous contaminants and is the focus of regulatory actions and risk assessments due to environmental spills. We exposed Daphnia magna to a gradient of coal ash contamination under high and low food rations to assess the sublethal effects of dietary exposures. Whereas exposure to contaminants resulted in significant reductions in growth and reproduction in daphnids, low, environmentally relevant food rations had a much greater effect on these endpoints. Environ Toxicol Chem 2020;39:1998-2007. © 2020 SETAC.

Methylmercury sorption onto engineered materials

Four commercially available sorbents (BioChar (BC), ThiolSAMMS^® (TS), SediMite (SM), and Organoclay™ PM-199 (OC-199)) were tested for their ability to sorb methylmercury (MeHg) and MeHg complexed with dissolved organic matter (DOM). Testing sorption behavior with DOM is more representative of the environmental conditions and mercury speciation expected during in-situ remediation efforts. Isotherms were fit using a robust, iterative re-weighting scheme. This fitting approach improves upon the traditionally used indirect sorption method by removing the dependence between aqueous and solid phase concentrations in isotherm fitting. Developed isotherms show that without DOM, BC, TS, and SM adsorbed similar amounts of MeHg while OC-199 sorbed substantially less MeHg. Below an equilibrium concentration of 5.6 ng L^-1 BC was the best performing sorbent, between 5.6 and 20.9 ng L^-1 SM sorbed the most MeHg, and above an equilibrium concentration of 20.9 ng L^-1 TS outperformed the other sorbents. BC and OC-199 showed indication of MeHg sorption saturation over the tested concentration range of 3.5-680 ng L^-1. With DOM, SM outperformed the other sorbents at equilibrium concentrations less than 0.98 ng L^-1 and TS was the superior MeHg:DOM sorbent at higher concentrations. MeHg:DOM sorption was controlled by DOM-sorbent interactions. DOM decreased MeHg sorption onto BC and SM whereas TS exhibited similar sorption with and without DOM. OC-199 had slightly higher MeHg uptake with DOM. East Fork Poplar Creek (EFPC), an industrially Hg contaminated site, was used as a case study example to build a relationship between aqueous and fish MeHg concentrations and subsequently compare the cost of sorbent materials required to meet regulatory objectives. For this case study, SM provided the most cost-effective sorbent option for in-situ remediation efforts to reduce aqueous MeHg concentrations.

Identifying non-reference sites to guide stream restoration and long-term monitoring

The reference condition paradigm has served as the standard for assessing the outcomes of restoration projects, particularly their success in meeting project objectives. One limitation of relying solely on the reference condition in designing and monitoring restoration projects is that reference conditions do not necessarily elucidate impairments to effective restoration, especially diagnosing the causal mechanisms behind unsuccessful outcomes. We provide a spatial framework to select both reference and non-reference streams to guide restoration planning and long-term monitoring through reliance on anthropogenically altered ecosystems to understand processes that govern ecosystem biophysical properties and ecosystem responses to restoration practices. We then applied the spatial framework to East Fork Poplar Creek (EFPC), Tennessee (USA), a system receiving 30years of remediation and pollution abatement actions from industrialization, pollution, and urbanization. Out of >13,000 stream reaches, we identified anywhere from 4 to 48 reaches, depending on the scenario, that could be used in restoration planning and monitoring for specific sites. Preliminary comparison of fish species composition at these sites compared to EFPC sites were used to identify potential mechanisms limiting the ecological recovery following remediation. We suggest that understanding the relative role of anthropogenic pressures in governing ecosystem responses is required to successful, process-driven restoration.

Heterogeneity in Nitrogen Sources Enhances Productivity and Nutrient Use Efficiency in Algal Polycultures

Algae hold much promise as a potential feedstock for biofuels and other products, but scaling up biomass production remains challenging. We hypothesized that multispecies assemblages, or polycultures, could improve crop yield when grown in media with mixed nitrogen sources, as found in wastewater. We grew mono- and poly- cultures of algae in four distinct growth media that differed in the form (i.e., nitrate, ammonium, urea, plus a mixture of all three) but not the concentration of nitrogen. We found that mean biomass productivity was positively correlated with algal species richness, and that this relationship was strongest in mixed nitrogen media (on average 88% greater biomass production in 5-species polycultures than in monocultures in mixed nitrogen treatment). We also found that the relationship between nutrient use efficiency and species richness was positive across nitrogen treatments, but greatest in mixed nitrogen media. While polycultures outperformed the most productive monoculture only 0-14% of the time in this experiment, they outperformed the average monoculture 26-52% of the time. Our results suggest that algal polycultures have the potential to be highly productive, and can be effective in recycling nutrients and treating wastewater, offering a sustainable and cost-effective solution for biofuel production.

Annual Summary of Vital Statistics: 2013-2014

The number of births in the United States increased by 1% between 2013 and 2014, to a total of 3 988 076. The general fertility rate rose 1% to 62.9 births per 1000 women. The total fertility rate also rose 0.3% in 2014, to 1862.5 births per 1000 women. The teenage birth rate fell to another historic low in 2014, 24.2 births per 1000 women. The percentage of all births to unmarried women declined to 40.2% in 2014, from 40.6% in 2013. In 2014, the cesarean delivery rate declined to 32.2% from 32.7% in 2013. The preterm birth rate declined for the seventh straight year in 2014 to 9.57%; the low birth weight rate was unchanged at 8.00%. The infant mortality rate decreased to a historic low of 5.82 infant deaths per 1000 live births in 2014. The age-adjusted death rate for 2014 was 7.2 deaths per 1000 population, down 1% from 2013. Crude death rates for children aged 1 to 19 years did not change significantly between 2013 and 2014. Unintentional injuries and suicide were, respectively, the first and second leading causes of death in this age group. These 2 causes of death jointly accounted for 46.5% of all deaths to children and adolescents in 2014.

Trends in Infant Mortality in the United States, 2005-2014

Infant mortality is considered a basic measure of public health for countries around the world (1-3). Over the past decade, the overall infant mortality rate in the United States has improved, declining 15% from 6.86 infant deaths per 1,000 live births in 2005-a recent high-to 5.82 in 2014 (4). Over the years, many efforts have been made to understand and lower infant mortality (4,5). This report examines the 2014 linked birth/infant death data from the National Vital Statistics System (NVSS) to describe trends in infant mortality in the United States by race and Hispanic origin, state, and leading causes of infant deaths from 2005 through 2014.

Births: Final Data for 2015

Objectives-This report presents 2015 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal age, live-birth order, race and Hispanic origin, marital status, attendant at birth, method of delivery, period of gestation, birthweight, and plurality. Selected data by mother's state of residence and birth rates by age and race of father also are shown. Trends in fertility patterns and maternal and infant characteristics are described and interpreted. Methods-Descriptive tabulations of data reported on the birth certificates of the 3.98 million births that occurred in 2015 are presented. Results-In 2015, 3,978,497 births were registered in the United States, down less than 1% from 2014. The general fertility rate was 62.5 per 1,000 women aged 15-44, a decline of 1% from 2014. The birth rate for teenagers aged 15-19 fell 8% in 2015, to 22.3 per 1,000 females. Birth rates declined for women in their 20s but increased for women in their 30s and early 40s. The total fertility rate (estimated number of births over a woman's lifetime) declined to 1,843.5 births per 1,000 women in 2015. The birth rate for unmarried women declined for the seventh straight year to 43.5 per 1,000. The cesarean delivery rate declined for the third year in a row to 32.0%. The preterm birth rate increased slightly from 2014, to 9.63% in 2015, as did the rate of low birthweight (8.07% in 2015). The twin birth rate declined to 33.5 per 1,000; the triplet and higher-order multiple birth rate was down 9% to 103.6 per 100,000.

Continued Declines in Teen Births in the United States, 2015

•The teen birth rate declined to another historic low for the United States in 2015, down 8% from 2014 to 22.3 births per 1,000 females aged 15-19. •The birth rates for teenagers aged 15-17 and 18-19 declined in 2015 to 9.9 and 40.7, respectively, which are record lows for both groups. •In 2015, birth rates declined to 6.9 for Asian or Pacific Islander, 16.0 for non-Hispanic white, 25.7 for American Indian or Alaska Native, 31.8 for non-Hispanic black, and 34.9 for Hispanic female teenagers aged 15-19. •Birth rates fell to record lows for nearly all race and Hispanic-origin groups of females aged 15-19, 15-17, and 18-19 in 2015. The birth rate for teenagers aged 15-19 has fallen almost continuously since 1991, reaching historic lows for the nation every year since 2009 (1-4). Despite declines in all racial and ethnic groups, teen birth rates continue to vary considerably by race and ethnicity. Moreover, the U.S. teen birth rate remains higher than in other industrialized countries (5). Childbearing by teenagers continues to be a matter of public concern. This report presents the recent and long-term trends and disparity in teen childbearing by race and Hispanic origin.

Relating fish health and reproductive metrics to contaminant bioaccumulation at the Tennessee Valley Authority Kingston coal ash spill site

A 4.1 million m(3) coal ash release into the Emory and Clinch rivers in December 2008 at the Tennessee Valley Authority's Kingston Fossil Plant in east Tennessee, USA, prompted a long-term, large-scale biological monitoring effort to determine if there are chronic effects of this spill on resident biota. Because of the magnitude of the ash spill and the potential for exposure to coal ash-associated contaminants [e.g., selenium (Se), arsenic (As), and mercury (Hg)] which are bioaccumulative and may present human and ecological risks, an integrative, bioindicator approach was used. Three species of fish were monitored-bluegill (Lepomis macrochirus), redear sunfish (L. microlophus), and largemouth bass (Micropterus salmoides)-at ash-affected and reference sites annually for 5 years following the spill. On the same individual fish, contaminant burdens were measured in various tissues, blood chemistry parameters as metrics of fish health, and various condition and reproduction indices. A multivariate statistical approach was then used to evaluate relationships between contaminant bioaccumulation and fish metrics to assess the chronic, sub-lethal effects of exposure to the complex mixture of coal ash-associated contaminants at and around the ash spill site. This study suggests that while fish tissue concentrations of some ash-associated contaminants are elevated at the spill site, there was no consistent evidence of compromised fish health linked with the spill. Further, although relationships between elevated fillet burdens of ash-associated contaminants and some fish metrics were found, these relationships were not indicative of exposure to coal ash or spill sites. The present study adds to the weight of evidence from prior studies suggesting that fish populations have not incurred significant biological effects from spilled ash at this site: findings that are relevant to the current national discussions on the safe disposal of coal ash waste.

Explaining the 2001–2002 Infant Mortality Increase in the United States: Data from the Linked Birth/Infant Death Data Set

The U.S. infant mortality rate (IMR) increased from 6.8 infant deaths per 1,000 live births in 2001 to 7.0 in 2002, the first increase in more than 40 years. From 2001 to 2002, IMR increased for very low birthweight infants as well as for preterm and very preterm infants. Although IMR for very low birthweight infants increased, most of the increase in IMR from 2001 to 2002 was due to a change in the distribution of births by birthweight and, more specifically, to an increase in infants born weighing less than 750 grams. The majority of infants born at less than 750 grams die within the first year of life; thus, these births contribute disproportionately to overall IMR. Increases in births at less than 750 grams occurred for non-Hispanic white, non-Hispanic black, and Hispanic women. Most of the increase occurred among mothers 20 to 34 years of age. Although multiple births contributed disproportionately, most of the increase in births at less than 750 grams occurred among singletons. Three hypotheses were evaluated to assess their possible impact on the increase in less than 750-gram births: possible changes in (1) the reporting of births or fetal deaths, (2) the risk profile of births, and (3) medical management of pregnancy. Although each of these factors may have contributed to the increase, the relative effects of these and other factors remain unclear. More detailed studies are needed to further explain the 2001–2002 infant mortality increase.

Mean Age of Mothers is on the Rise: United States, 2000-2014

Data from the National Vital Statistics System. The mean age of mothers has increased from 2000 to 2014 for all birth orders, with age at first birth having the largest increase, up from 24.9 years in 2000 to 26.3 years in 2014. Increases in the average age for all birth orders were most pronounced from 2009 to 2014. In 2014, Asian or Pacific Islander mothers had the oldest average age at first birth (29.5 years), while American Indian or Alaska Native mothers had the youngest (23.1 years). Mean age at first birth increased in all states and the District of Columbia (D.C.) from 2000 to 2014, but D.C. (3.4 years) and Oregon had the largest increases (2.1 years).

The effects of a stannous chloride-based water treatment system in a mercury contaminated stream

We assessed the impacts of an innovative Hg water treatment system on a small, industrially-contaminated stream in the southeastern United States. The treatment system, installed in 2007, removes Hg from wastewater using tin (Sn) (II) chloride followed by air stripping. Mercury concentrations in the receiving stream, Tims Branch, decreased from >100 to ∼10 ng/L in the four years following treatment, and Hg body burdens in redfin pickerel (Esox americanus) decreased by 70% at the most contaminated site. Tin concentrations in water and fish increased significantly in the tributary leading to Tims Branch, but concentrations remain below levels of concern for human health or ecological risks. While other studies have shown that Sn may be environmentally methylated and methyltin can transfer its methyl group to Hg, results from our field studies and sediment incubation experiments suggest that the added Sn to the Tims Branch watershed is not contributing to methylmercury (MeHg) production or bioaccumulation in this system. The stannous chloride treatment system installed at Tims Branch was effective at removing Hg inputs and reducing Hg bioaccumulation in the stream, but future studies are needed to assess longer term impacts of Sn on the environment.

When are babies born: morning, noon, or night? Birth certificate data for 2013

The highest percentages of births occurred during the morning and midday hours. Births on Saturday and Sunday were more likely to occur in the late evening and early morning hours than births Monday through Friday. Compared with induced vaginal deliveries and noninduced vaginal deliveries, cesarean deliveries were the least likely to occur during the evening and early morning. Noninduced vaginal births were more likely than cesarean and induced vaginal births to occur in the early morning. Cesarean deliveries with no trial of labor were much more concentrated during the day than were cesarean deliveries with a trial of labor. Births delivered in hospitals and all births show similar time-of-day patterns.

Selenium bioaccumulation in fish exposed to coal ash at the Tennessee Valley Authority Kingston spill site

In December 2008, 4.1 million cubic meters of coal ash were released into the Emory and Clinch Rivers by the Tennessee Valley Authority Kingston Fossil Plant. Coal ash contains several contaminants, including the bioaccumulative metalloid selenium (Se). Because Se is predominantly accumulated in aquatic organisms through dietary rather than aqueous exposure, tissue-based toxicity thresholds for Se are currently being considered. The proposed threshold concentrations range between 4 μg/g and 9 μg/g Se (dry wt.) in whole body fish, with a proposed fillet threshold of 11.8 μg/g. In the present study, the authors examined the spatial and temporal trends in Se bioaccumulation and examined the relationship between the Se content in fillets and in whole bodies of fish collected around the Kingston spill site to determine whether Se bioaccumulation was a significant concern at the ash spill site. Whereas Se concentrations in fish (whole bodies and fillets) were elevated at sampling locations affected by the Kingston ash spill relative to reference locations, concentrations do not appear to be above risk thresholds and have not been increasing over the 5-yr period since the spill. These findings are not only relevant to guiding the human health and ecological risk assessments at the Kingston ash spill site, but because of current national discussions on appropriate guidelines for Se in fish as well for the disposal of coal combustion wastes, the results are also relevant to the general understanding of Se bioaccumulation in contaminated water bodies.

Pregnancy and childbirth among females aged 10-19 years - United States, 2007-2010

Pregnancy and childbirth among females aged <20 years have been the subject of long-standing concern among the public, the public health community, and policy makers. Teenagers who give birth are much more likely than older women to deliver a low birthweight or preterm infant, and their babies are at higher risk for dying in infancy. The annual public costs associated with births among teenage girls are an estimated $10.9 billion. According to the 2006-2010 National Survey of Family Growth (NSFG), an estimated 77% of births to teenagers aged 15-19 years were unintended.

Infant deaths - United States, 2005-2008

Infant mortality rates are associated with maternal health, quality of and access to medical care, socioeconomic conditions, and public health practices, which makes infant mortality an increasingly important public health concern. After large declines throughout the twentieth century, the U.S. infant mortality rate did not decline significantly during 2000-2005. Analysis of 2000-2004 infant mortality in the United States indicated considerable disparities by race and Hispanic origin. Race and ethnic disparities in U.S. infant mortality have been apparent since vital statistics data began to be collected more than 100 years ago. These disparities have persisted over time, and research indicates that not all groups have benefited equally from social and medical advances.

Recent Trends in Out-of-Hospital Births in the United States

INTRODUCTION

Although out-of-hospital births are still relatively rare in the United States, it is important to monitor trends in these births, as they can affect patterns of facility usage, clinician training, and resource allocation, as well as health care costs. Trends and characteristics of home and birth center births are analyzed to more completely profile contemporary out-of-hospital births in the United States.

METHODS

National birth certificate data were used to examine a recent increase in out-of-hospital births.

RESULTS

After a gradual decline from 1990 to 2004, the number of out-of-hospital births increased from 35,578 in 2004 to 47,028 in 2010. In 2010, 1 in 85 US infants (1.18%) was born outside a hospital; about two-thirds of these were born at home, and most of the rest were born in birth centers. The proportion of home births increased by 41%, from 0.56% in 2004 to 0.79% in 2010, with 10% of that increase occurring in the last year. The proportion of birth center births increased by 43%, from 0.23% in 2004 to 0.33% in 2010, with 14% of the increase in the last year. About 90% of the total increase in out-of hospital births from 2004 to 2010 was a result of increases among non-Hispanic white women, and 1 in 57 births to non-Hispanic white women (1.75%) in 2010 was an out-of-hospital birth. Most home and birth center births were attended by midwives.

DISCUSSION

Home and birth center births in the United States are increasing, and the rate of out-of-hospital births is now at the highest level since 1978. There has been a decline in the risk profile of out-of-hospital births, with a smaller proportion of out-of-hospital births in 2010 than in 2004 occurring to adolescents and unmarried women and fewer preterm, low-birth-weight, and multiple births.

Births: final data for 2011

OBJECTIVES

This report presents 2011 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal characteristics, including age, live-birth order, race and Hispanic origin, marital status, attendant at birth, method of delivery, and infant characteristics (e.g., period of gestation, birthweight, and plurality). Birth and fertility rates are presented by age, live-birth order, race and Hispanic origin, and marital status. Selected data by mother's state of residence and birth rates by age and race of father also are shown. Trends in fertility patterns and maternal and infant characteristics are described and interpreted.

METHODS

Descriptive tabulations of data reported on the birth certificates of the 3.95 million births that occurred in 2011 are presented. Denominators for population-based rates are postcensal estimates derived from the U.S. 2010 census. Birth and fertility rates for 2001-2009 are based on revised intercensal population estimates. Denominators for 2011 and 2010 rates for the specific Hispanic groups are derived from the American Community Survey; denominators for earlier years are derived from the Current Population Survey.

RESULTS

The number of births declined 1% in 2011 to 3,953,590. The general fertility rate also declined 1%, to 63.2 per 1,000 women aged 15-44. The teen birth rate fell 8%, to 31.3 per 1,000 women. Birth rates declined for women in their 20s, were unchanged for women aged 30-34, and rose for women aged 35-44. The total fertility rate (estimated number of births over a woman's lifetime) declined 2% to 1,894 per 1,000 women. The number and rate of births to unmarried women declined; the percentage of births to unmarried women was essentially stable at 40.7%. The cesarean delivery rate was unchanged from 2010 at 32.8%. The preterm birth rate declined for the fifth straight year to 11.73%; the low birthweight rate declined slightly to 8.10%. The twin birth rate was not significantly changed at 33.2 per 1,000 births; the rate of triplet and higher-order multiple births also was essentially stable at 137.0 per 100,000.

Declines in state teen birth rates by race and Hispanic origin

Teen birth rates fell steeply in the United States from 2007 through 2011, resuming a decline that began in 1991 but was briefly interrupted in 2006 and 2007. The overall rate declined 25% from 41.5 per 1,000 teenagers aged 15-19 in 2007 to 31.3 in 2011--a record low. The number of births to teenagers aged 15-19 also fell from 2007 to 2011, by 26% to 329,797 in 2011. Births to teenagers are at elevated risk of low birthweight, preterm birth, and of dying in infancy compared with infants born to women aged 20 and over, and they are associated with significant public costs, estimated at $10.9 billion annually. Recent trends by state and race and Hispanic origin are illustrated using the most current available data from the National Vital Statistics System.

Recent declines in infant mortality in the United States, 2005-2011

After a plateau from 2000 through 2005, the U.S. infant mortality rate declined by 12% to a rate of 6.05 in 2011. Provisional infant mortality counts for the first half of 2012 suggest a continued downward trend. Infant mortality declined from 2005 through 2011 for all major racial and ethnic groups, with the most rapid decline among non-Hispanic black women. Among leading causes of death, infant mortality declined for four of the five leading causes. Infant mortality rates declined most rapidly from 2005 through 2010 for selected Southern states; still, rates in 2010 remained higher in the South and Midwest than in other regions. In 2008, the United States ranked 27th in infant mortality rate among Organization for Economic Cooperation and Development countries, and a previous report linked the United States’ relatively unfavorable infant mortality ranking to its higher percentage of preterm births. Despite the recent infant mortality decline, comparing the 2011 U.S. infant mortality rate with the 2008 international rankings would still have the United States ranked 27th.

Infant mortality statistics from the 2009 period linked birth/infant death data set

OBJECTIVES

This report presents 2009 period infant mortality statistics from the linked birth/infant death data set (linked file) by maternal and infant characteristics. The linked file differs from the mortality file, which is based entirely on death certificate data.

METHODS

Descriptive tabulations of data are presented and interpreted.

RESULTS

The infant mortality rate in the United States in 2009 was 6.39 infant deaths per 1,000 live births, 3% lower than the rate of 6.61 in 2008. The number of infant deaths was 28,075 in 2008 and 26,408 in 2009, a decline of 1,667 infant deaths. Infant mortality rates ranged from 4.40 per 1,000 live births for Asian or Pacific Islander mothers to 12.40 for non-Hispanic black mothers. Infant mortality was higher for male infants and infants born preterm or at low birthweight. Infant mortality rates were also higher for those infants who were born in multiple deliveries, to mothers who were unmarried, and for those whose mothers were born in the 50 states or the District of Columbia. From 2008 to 2009, the neonatal mortality rate (under age 28 days) declined 3% to 4.18 neonatal deaths per 1,000 live births, while the postneonatal mortality rate (aged 28 days to under 1 year) declined 5% to 2.21. Preterm and low birthweight infants had the highest infant mortality rates and contributed greatly to overall U.S. infant mortality. The three leading causes of infant death--congenital malformations, low birthweight, and sudden infant death syndrome--accounted for 46% of all infant deaths. In 2009, 35.4% of infant deaths were "preterm-related."

Decreasing aqueous mercury concentrations to meet the water quality criterion in fish: examining the water-fish relationship in two point-source contaminated streams

East Fork Poplar Creek (EF) and White Oak Creek (WC) are two mercury-contaminated streams located on the United States (U.S.) Department of Energy Oak Ridge Reservation in East Tennessee. East Fork Poplar Creek is the larger and more contaminated of the two, with average aqueous mercury (Hg) concentrations exceeding those in reference streams by several hundred-fold. Remedial actions over the past 20 years have decreased aqueous Hg concentrations in EF by 85% (from >1600 ng/L to <400 ng/L). Fish fillet concentrations, however, have not responded to this decrease in aqueous Hg and remain above the U.S. Environmental Protection Agency National Recommended Water Quality Criteria (NRWQC) of 0.3 mg/kg. The lack of correlation between aqueous and fish tissue Hg concentrations in this creek has led to questions regarding the usefulness of target aqueous Hg concentrations and strategies for future remediation efforts. White Oak Creek has a similar contamination history but aqueous Hg concentrations in WC are an order of magnitude lower than in EF. Despite the lower aqueous Hg concentrations (<100 ng/L), fish fillet concentrations in WC have also been above the NRWQC, making the aqueous Hg remediation goal of 200 ng/L in EF seem unlikely to result in an effective decrease in fillet Hg concentrations. Recent monitoring efforts in WC, however, suggest an aqueous total Hg threshold above which Hg bioaccumulation in fish may not respond. This new information could be useful in guiding remedial actions in EF and in other point-source contaminated streams.

Births: final data for 2010

OBJECTIVES

This report presents 2010 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal characteristics including age, live-birth order, race and Hispanic origin, marital status, attendant at birth, method of delivery, and infant characteristics (period of gestation, birthweight, and plurality). Birth and fertility rates by age, live-birth order, race and Hispanic origin, and marital status also are presented. Selected data by mother's state of residence are shown, as well as birth rates by age and race of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted.

METHODS

Descriptive tabulations of data reported on the birth certificates of the 4.0 million births that occurred in 2010 are presented. Denominators for population-based rates are postcensal estimates derived from the U.S. 2010 census.

RESULTS

The number of births declined to 3,999,386 in 2010, 3 percent less than in 2009. The general fertility rate also declined 3 percent, to 64.1 per 1,000 women aged 15-44. The teen birth rate fell 10 percent to 34.2 per 1,000. Birth rates for women in each 5-year age group from 20 through 39 years declined, but the rate for women aged 40-44 continued to rise. The total fertility rate (estimated number of births over a woman's lifetime) was down 4 percent to 1,931 per 1,000 women. The number, rate, and percentage of births to unmarried women declined. The cesarean deliver rate was down for the first year since 1996 to 32.8 percent. The preterm birth rate declines for the fourth year in a row to 11.99 percent; the low birthweight rate was stable at 8.15 percent. The twin birth rate declined slightly to 33.1 per 1,000 births; the triplet and higer-order multipe birth rate dropped 10 percent to 137.6 per 100,000.

Infant mortality statistics from the 2008 period linked birth/infant death data set

OBJECTIVES

This report presents 2008 period infant mortality statistics from the linked birth/infant death data set (linked file) by a variety of maternal and infant characteristics. The linked file differs from the mortality file, which is based entirely on death certificate data.

METHODS

Descriptive tabulations of data are presented and interpreted.

RESULTS

The U.S. infant mortality rate was 6.61 infant deaths per 1,000 live births in 2008, 2 percent lower than the rate of 6.75 in 2007. Infant mortality rates ranged from 4.51 per 1,000 live births for Asian or Pacific Islander mothers to 12.67 for non-Hispanic black mothers. The rate for non-Hispanic black women declined 5 percent from 2007 to 2008. Infant mortality was higher for male infants and infants born preterm or at low birthweight. Infant mortality rates were also higher for those infants who were born in multiple deliveries, to mothers who were unmarried, and for those whose mothers were born in the 50 states or the District of Columbia. From 2007 to 2008, the neonatal mortality rate (under age 28 days) declined by 3 percent to 4.29 neonatal deaths per 1,000 live births, while the postneonatal mortality rate (aged 28 days to under 1 year) remained essentially unchanged (2.32). Preterm and low birthweight infants had the highest infant mortality rates and contributed greatly to the overall U.S. infant mortality. The three leading causes of infant death--congenital malformations, low birthweight, and sudden infant death syndrome--accounted for 46 percent of all infant deaths. In 2008, 35.4 percent of infant deaths were "preterm-related."

Home births in the United States, 1990-2009

After 14 years of decline, the percentage of home births rose by 29% from 2004 to 2009, to the point where it is at the highest level since data on this item began to be collected in 1989. The overall increase in home births was driven mostly by a 36% increase for non-Hispanic white women. About 1 out of every 90 births to non-Hispanic white women are now home births. The percentage of home births for non-Hispanic white women was three to five times higher than for any other racial or ethnic group. Home births have a lower risk profile than hospital births, with fewer births to teenagers or unmarried women, and with fewer preterm, low birthweight, and multiple births. The lower risk profile of home compared with hospital births suggests that home birth attendants are selecting low-risk women as candidates for home birth. The increase in the percentage of home births from 2004 to 2009 was widespread and involved selected states from every region of the country. The large variations in the percentage of home births by state may be influenced by differences among states in laws pertaining to births are more prevalent among non-Hispanic white women (7). midwifery practice or out-of-hospital birth (8,9), as well as by differences in the racial and ethnic composition of state populations, as home Studies have suggested that most home births are intentional or planned home births, whereas others are unintentional or unplanned, because of an emergency situation (i.e., precipitous labor, labor complications, or unable to get to the hospital in time) (3,6). Although not representative of all U.S. births (see "Data source and methods"), 87% of home births in a 26-state reporting area (comprising 50% of U.S. births) were planned in 2009. For non-Hispanic white women, 93% of home births were planned (10). Women may prefer a home birth over a hospital birth for a variety of reasons, including a desire for a low-intervention birth in a familiar environment surrounded by family and friends, and cultural or religious concerns (9,11). Lack of transportation in rural areas and cost factors may also play a role, as home births cost about one-third as much as hospital births (9,11,12).

Births: final data for 2009

OBJECTIVES

This report presents 2009 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal characteristics including age, live-birth order, race and Hispanic origin, marital status, hypertension during pregnancy, attendant at birth, method of delivery, and infant characteristics (period of gestation, birthweight, and plurality). Birth and fertility rates by age, live-birth order, race and Hispanic origin, and marital status also are presented. Selected data by mother's state of residence are shown, as well as birth rates by age and race of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted.

METHODS

Descriptive tabulations of data reported on the birth certificates of the 4.13 million births that occurred in 2009 are presented. Denominators for population-based rates are postcensal estimates derived from the U.S. 2000 census.

RESULTS

The number of births declined to 4,130,665 in 2009, 3 percent less than in 2008. The general fertility rate declined 3 percent to 66.7 per 1,000 women aged 15-44 years. The teenage birth rate fell 6 percent to 39.1 per 1,000. Birth rates for women in each 5-year age group from 20 through 39 years declined, but the rate for women 40-44 years continued to rise. The total fertility rate (estimated number of births over a woman's lifetime) was down 4 percent to 2,007.0 per 1,000 women. The number and rate of births to unmarried women declined, whereas the percentage of nonmarital births increased slightly to 41.0. The cesarean delivery rate rose again, to 32.9 percent. The preterm birth rate declined to 12.18 percent; the low birthweight rate was stable at 8.16 percent. The twin birth rate increased to 33.2 per 1,000; the triplet and higher-order multiple birth rate rose 4 percent to 153.5 per 100,000.

United States home births increase 20 percent from 2004 to 2008

BACKGROUND

After a gradual decline from 1990 to 2004, the percentage of births occurring at home increased from 2004 to 2008 in the United States. The objective of this report was to examine the recent increase in home births and the factors associated with this increase from 2004 to 2008.

METHODS

United States birth certificate data on home births were analyzed by maternal demographic and medical characteristics.

RESULTS

In 2008, there were 28,357 home births in the United States. From 2004 to 2008, the percentage of births occurring at home increased by 20 percent from 0.56 percent to 0.67 percent of United States births. This rise was largely driven by a 28 percent increase in the percentage of home births for non-Hispanic white women, for whom more than 1 percent of births occur at home. At the same time, the risk profile for home births has been lowered, with substantial drops in the percentage of home births of infants who are born preterm or at low birthweight, and declines in the percentage of home births that occur to teen and unmarried mothers. Twenty-seven states had statistically significant increases in the percentage of home births from 2004 to 2008; only four states had declines.

CONCLUSION

The 20 percent increase in United States home births from 2004 to 2008 is a notable development that will be of interest to practitioners and policymakers. (BIRTH 38:3 September 2011).

Understanding racial and ethnic disparities in U.S. infant mortality rates

In the United States, different racial and ethnic groups have very different infant mortality patterns. When assessing the relative contribution of the percentage of preterm births and gestational age-specific infant mortality rates to racial and ethnic infant mortality differences, we found that for non-Hispanic black women, 78 percent of their elevated infant mortality rate compared with non-Hispanic white women was due to their higher percentage of preterm births, while 22 percent was due to higher gestational age-specific infant mortality rates (primarily at 34 weeks of gestation or more). For Puerto Rican women, their elevated infant mortality rate compared with non-Hispanic white women was entirely due to their higher percentage of preterm births. However, AIAN women had a very different infant mortality pattern: 76 percent of their higher infant mortality rate compared with non-Hispanic white women was due to their higher gestational age-specific infant mortality rates (primarily at 34 weeks or more), and only 24 percent was due to their higher percentage of preterm births.These findings are consistent with the cause-of-death analysis, which found that for bothnon-Hispanic black and Puerto Rican women, most of their higher infant mortality rate compared with non-Hispanic white women was due to preterm-related causes. In contrast, for AIAN women, the infant mortality rate from SIDS was 2.4 times, and the rate from unintentional injuries was 2.3 times, the non-Hispanic white rate. Infant mortality rates for non-Hispanic black women would be reduced by 71 percent, those for AIAN women by 64 percent, and those for Puerto Rican women by 67 percent if rates from preterm-related causes, congenital malformations, SIDS, and unintentional injuries could be reduced to non-Hispanic white levels.The different infant mortality patterns for non-Hispanic black, Puerto Rican, and AIAN women suggest different prevention strategies (6,7). In addition, because the percentage of preterm births for all U.S. racial and ethnic groups is higher than in other developed countries, all U.S. racial and ethnic groups might benefit from prematurity prevention efforts (8,9).

Expanded data from the new birth certificate, 2008

OBJECTIVES

This report presents data for selected items exclusive to the 2003 U.S. Standard Certificate of Live Birth as well as key items considered not comparable between the 1989 (unrevised) and 2003 (revised) versions for states and territories that implemented the 2003 revision as of January 1, 2008. Information is shown for educational attainment, tobacco use during pregnancy, month prenatal care began, and checkboxes in the following categories: "risk factors in this pregnancy," "obstetric procedures," "characteristics of labor and delivery," "method of delivery," "abnormal conditions of the newborn," and "congenital anomalies of the newborn."

METHODS

Descriptive statistics are presented on births occurring in 2008 to residents of the 27 states that implemented the revised birth certificate.

RESULTS

There were 2,748,302 births to residents of the 27-state reporting area, representing 65 percent of 2008 U.S. births. About 78 percent of women had at least a high school diploma; 24.5 percent had an advanced education. One out of 10 women smoked during pregnancy (24-state reporting area) and one out of five smokers quit while pregnant. Almost three-quarters of women began prenatal care in the first trimester of pregnancy. The rate of prepregnancy diabetes was 6.5 per 1,000 and gestational diabetes was 40.6; risk of both types rose with maternal age. Nearly one out of four women had a primary cesarean delivery; less than 1 out of 10 women had a vaginal birth after cesarean delivery. About 27 percent of women attempted a trial of labor before a cesarean delivery. Seven percent of all infants were admitted to a neonatal intensive care unit.

Infant mortality statistics from the 2007 period linked birth/infant death data set

OBJECTIVES

This report presents 2007 period infant mortality statistics from the linked birth/infant death data set (linked file) by a variety of maternal and infant characteristics. The linked file differs from the mortality file, which is based entirely on death certificate data.

METHODS

Descriptive tabulations of data are presented and interpreted.

RESULTS

The U.S. infant mortality rate was 6.75 infant deaths per 1,000 live births in 2007, not significantly different than the rate of 6.68 in 2006. Infant mortality rates ranged from 4.57 per 1,000 live births for mothers of Central and South American origin to 13.31 for non-Hispanic black mothers. Infant mortality rates were higher for those infants who were born in multiple deliveries; for those whose mothers were born in the 50 states or the District of Columbia; and for mothers who were unmarried. Infant mortality was also higher for male infants and infants born preterm or at low birthweight. The neonatal mortality rate was essentially unchanged from 2006 (4.46) to 2007 (4.42). The postneonatal mortality rate increased 5 percent from 2.22 in 2006 to 2.33 in 2007, similar to the rate in 2005 (2.32). Infants born at the lowest gestational ages and birthweights have a large impact on overall U.S. infant mortality. For example, more than one-half of all infant deaths in the United States in 2007 (54 percent) occurred to the 2 percent of infants born very preterm (less than 32 weeks of gestation). Still, infant mortality rates for late preterm infants (34-36 weeks of gestation) were 3.6 times, and those for early term (37-38 weeks) infants were 1.5 times, those for infants born at 39-41 weeks of gestation, the gestational age with the lowest infant mortality rate. The three leading causes of infant death--congenital malformations, low birthweight, and sudden infant death syndrome--accounted for 45 percent of all infant deaths. The percentage of infant deaths that were "preterm-related" was 36.0 percent in 2007. The preterm-related infant mortality rate for non-Hispanic black mothers was 3.4 times higher, and the rate for Puerto Rican mothers was 71 percent higher than for non-Hispanic white mothers.

Monitoring fish contaminant responses to abatement actions: factors that affect recovery

Monitoring of contaminant accumulation in fish has been conducted in East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee since 1985. Bioaccumulation trends are examined over a twenty year period coinciding with major pollution abatement actions by a Department of Energy facility at the stream's headwaters. Although EFPC is enriched in many contaminants relative to other local streams, only polychlorinated biphenyls (PCBs) and mercury (Hg) were found to accumulate in the edible portions of fish to levels of human health concern. Mercury concentrations in redbreast sunfish were found to vary with season of collection, sex and size of individual fish. Over the course of the monitoring, waterborne Hg concentrations were reduced >80%; however, this did not translate into a comparable decrease in Hg bioaccumulation at most sites. Mercury bioaccumulation in fish did respond to decreased inputs in the industrialized headwater reach, but paradoxically increased in the lowermost reach of EFPC. As a result, the downstream pattern of Hg concentration in fish changed from one resembling dilution of a headwater point source in the 1980s to a uniform distribution in the 2000s. The reason for this remains unknown, but is hypothesized to involve changes in the chemical form and reactivity of waterborne Hg associated with the removal of residual chlorine and the addition of suspended particulates to the streamflow. PCB concentrations in fish varied greatly from year-to-year, but always exhibited a pronounced downstream decrease, and appeared to respond to management practices that limited episodic inputs from legacy sources within the facility.

Recent decline in births in the United States, 2007-2009

From 2007 through 2009, birth rates for women aged 15-44 (fertility rates) fell for most states and nearly all major population subgroups. Birth rates declined for all women under age 40 with some of the largest decreases for women in their peak childbearing years. Fertility rates dropped for all major racial and Hispanic groups with the largest declines among Hispanic women. Birth rates by live-birth order also fell with the largest declines for third-order births and progressively smaller declines for second- and first-order births. Fertility rates decreased or were unchanged in every state and the District of Columbia with the largest declines among western and southeastern states. The number of births in the United States reached an all-time high of 4,316,233 in 2007, but that number has since fallen. From 2007 through 2009, births fell 4 percent to 4,131,019; and the provisional count of births through June 2010 indicated continued declines. Fertility rates--which relate the number of births to women aged 15-44 (i.e., the childbearing years)--also fell during this time frame.This report takes a more detailed look at the decline in births from 2007 through 2009 by mother's age, race and ethnicity, birth order, and state. The analysis is based on a comparison of 2007 final and 2009 preliminary birth data from the National Vital Statistics System (NVSS), and are the most current detailed birth data available.

Annual summary of vital statistics: 2008

The number of births in the United States decreased between 2007 and 2008 (preliminary estimate: 4 251 095). Birth rates declined among all women aged 15 to 39 years; the decrease among teenagers reverses the increases seen in the previous 2 years. The total fertility rate decreased 2% in 2008 to 2085.5 births per 1000 women. The proportion of all births to unmarried women increased to 40.6% in 2008, up from 39.7% in 2007. The 2008 preterm birth rate was 12.3%, a decline of 3% from 2007. In 2008, 32.3% of all births occurred by cesarean delivery, up nearly 2% from 2007. Twin and triplet birth rates were unchanged. The infant mortality rate was 6.59 infant deaths per 1000 live births in 2008 (significantly lower than the rate of 6.75 in 2007). Life expectancy at birth was 77.8 years in 2008. Crude death rates for children aged 1 to 19 years decreased by 5.5% between 2007 and 2008. Unintentional injuries and homicide were, respectively, the first and second leading causes of death in this age group. These 2 causes of death jointly accounted for 51.2% of all deaths of children and adolescents in 2008. This annual article is a long-standing feature in Pediatrics and provides a summary of the most current vital statistics data for the United States. We also include a special feature this year on the differences in cesarean-delivery rates according to race and Hispanic origin.

Behind international rankings of infant mortality: how the United States compares with Europe

In 2005, the United States ranked 30th in the world in infant mortality. Infant mortality rates for preterm (<37 weeks of gestation) infants are lower in the United States than in most European countries; however, infant mortality rates for infants born at 37 or more weeks of gestation are higher in the United States than in most European countries. One in 8 births in the United States were preterm in 2005, compared with 1 in 18 births in Ireland and Finland, and 1 in 16 in France and Sweden. If the United States had Sweden's distribution of births by gestational age, nearly 8,000 infant deaths in the United States would be averted each year, and the U.S. infant mortality rate would be one-third lower. The main cause of the United States' high infant mortality rate when compared with Europe is the very high percentage of preterm births in the United States, the period when infant mortality is greatest.

Births: final data for 2008

OBJECTIVES

This report presents 2008 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal demographic characteristics including age, live-birth order, race and Hispanic origin, marital status, attendant at birth, method of delivery, and infant characteristics (period of gestation, birthweight, and multiple births). Birth and fertility rates by age, live-birth order, race and Hispanic origin, and marital status also are presented. Selected data by mother's state of residence are shown, as well as data on age of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted.

METHODS

Descriptive tabulations of data reported on the birth certificates of the 4.25 million births that occurred in 2008 are presented. Denominators for population-based rates are postcensal estimates derived from the U.S. 2000 census.

RESULTS

A total of 4,247,694 births were registered in the United States in 2008, 2 percent less than in 2007. The general fertility rate declined 1 percent to 68.6 per 1,000. The teenage birth rate declined 2 percent to 41.5 per 1,000. Birth rates for women aged 20 to 39 years were down 1-3 percent, whereas the birth rate for women aged 40-44 rose to the highest level reported in more than 40 years. The total fertility rate declined 2 percent to 2,084.5 per 1,000 women. All measures of unmarried childbearing reached record levels-40.6 percent of births were to unmarried women in 2008. The cesarean delivery rate rose again to 32.3 percent. The preterm birth rate declined for the second consecutive year to 12.3 percent; the low birthweight rate was down very slightly. The twin birth rate increased 1 percent to 32.6 per 1,000; the triplet and higher-order multiple birth rate was stable.

State disparities in teenage birth rates in the United States

In 2008, state-specific teenage birth rates varied widely, from less than 25.0 per 1,000 15-19 year olds to more than 60.0. Rates for non-Hispanic white and Hispanic teenagers were uniformly higher in the Southeast and lower in the Northeast and California. The highest rates for non-Hispanic black teenagers were reported in the upper Midwest and in the Southeast. The race and Hispanic origin-specific birth rates by state as well as the population composition of states by race and Hispanic origin contribute to state variations in overall teenage birth rates.

Births: final data for 2007

OBJECTIVES

This report presents 2007 data on U.S. births according to a wide variety of characteristics; preliminary 2008 data are also referenced on key measures where available. Final 2007 data are presented for maternal demographic characteristics including age, live-birth order, race and Hispanic origin, marital status, and educational attainment; maternal lifestyle and health characteristics (medical risk factors, weight gain, and tobacco use); medical care utilization by pregnant women (prenatal care, obstetric procedures, characteristics of labor and/or delivery, attendant at birth, and method of delivery); and infant characteristics (period of gestation, birthweight, Apgar score, congenital anomalies, and multiple births). Birth and fertility rates by age, live-birth order, race and Hispanic origin, and marital status also are presented. Selected data by mother's state of residence are shown, as well as data on month and day of birth, sex ratio, and age of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted.

METHODS

Descriptive tabulations are presented of data reported on the birth certificates of the 4.3 million births that occurred in 2007. Preliminary 2008 data are based on 99.9 percent of births occurring in 2008. Denominators for population-based rates are postcensal estimates derived from the U.S. 2000 census.

RESULTS

A total of 4,316,233 births were registered in the United States in 2007, the largest number of births ever reported. The general fertility rate increased 1 percent to 69.5 per 1,000. Birth rates increased for women in nearly all age groups. The rate for teenagers rose 1 percent for the year and is up 5 percent from 2005. The total fertility rate increased 1 percent to 2,122.0 births per 1,000 women. Preliminary data for 2008, however, suggest a decline in the number and rate of births overall, and for most age groups under age 40 years. All measures of unmarried childbearing reached record levels in 2007. The cesarean delivery rate rose to another all-time high--31.8 percent. Preterm and low birthweight rates declined slightly, and twin and triplet and higher-order multiple birth rates were essentially unchanged. Preliminary findings for 2008 suggest that these trends continued for cesarean delivery, unmarried childbearing, and preterm births.

Infant mortality statistics from the 2006 period linked birth/infant death data set

OBJECTIVES

This report presents 2006 period infant mortality statistics from the linked birth/infant death data set (linked file) by a variety of maternal and infant characteristics. The linked file differs from the mortality file, which is based entirely on death certificate data.

METHODS

Descriptive tabulations of data are presented and interpreted.

RESULTS

The U.S. infant mortality rate was 6.68 infant deaths per 1,000 live births in 2006, a 3 percent decline from 6.86 in 2005. Infant mortality rates ranged from 4.52 per 1,000 live births for Central and South American mothers to 13.35 for non-Hispanic black mothers. Infant mortality rates were higher for those infants whose mothers were born in the 50 states or the District of Columbia, were unmarried, or were born in multiple deliveries. Infant mortality was also higher for male infants and infants born preterm or at low birthweight. The neonatal mortality rate was essentially unchanged in 2006 (4.46) from 2005 (4.54). The postneonatal mortality rate decreased 4 percent, from 2.32 in 2005 to 2.22 in 2006. Infants born at the lowest gestational ages and birthweights have a large impact on overall U.S. infant mortality. For example, more than half of all infant deaths in the United States in 2006 (54 percent) occurred to the 2 percent of infants born very preterm (less than 32 weeks of gestation). Still, infant mortality rates for late preterm infants (34-36 weeks of gestation) were three times those for term infants (37-41 weeks). The three leading causes of infant death--congenital malformations, low birthweight, and sudden infant death syndrome--taken together accounted for 46 percent of all infant deaths. The percentage of infant deaths that were "preterm-related" was 36.1 percent in 2006. The preterm-related infant mortality rate for non-Hispanic black mothers was 3.4 times higher and the rate for Puerto Rican mothers was 84 percent higher than for non-Hispanic white mothers.

Behind international rankings of infant mortality: how the United States compares with Europe

Infant mortality is an important indicator of the health of a nation, and the recent stagnation (since 2000) in the U.S. infant mortality rate has generated concern among researchers and policy makers. The percentage of preterm births in the United States has risen 36% since 1984 (1). In this report we compare infant mortality rates between the United States and Europe. We also compare two factors that determine the infant mortality rate-gestational age-specific infant mortality rates and the percentage of preterm births. U.S. data are from the Linked Birth/Infant Death Data Set (2,3), and European data for 2004 are from the recently published European Perinatal Health Report (4). We also examine requirements for reporting a live birth among countries to assess the possible effect of reporting differences on infant mortality data.

Control selection and participation in an ongoing, population-based, case-control study of birth defects: the National Birth Defects Prevention Study

To evaluate the representativeness of controls in an ongoing, population-based, case-control study of birth defects in 10 centers across the United States, researchers compared 1997-2003 birth certificate data linked to selected controls (n = 6,681) and control participants (n = 4,395) with those from their base populations (n = 2,468,697). Researchers analyzed differences in population characteristics (e.g., percentage of births at > or =2,500 g) for each group. Compared with their base populations, control participants did not differ in distributions of maternal or paternal age, previous livebirths, maternal smoking, or diabetes, but they did differ in other maternal (i.e., race/ethnicity, education, entry into prenatal care) and infant (i.e., birth weight, gestational age, and plurality) characteristics. Differences in distributions of maternal, but not infant, characteristics were associated with participation by selected controls. Absolute differences in infant characteristics for the base population versus control participants were < or =1.3 percentage points. Differences in infant characteristics were greater at centers that selected controls from hospitals compared with centers that selected controls from electronic birth certificates. These findings suggest that control participants in the National Birth Defects Prevention Study generally are representative of their base populations. Hospital-based control selection may slightly underascertain infants affected by certain adverse birth outcomes.

The challenge of infant mortality: have we reached a plateau?

OBJECTIVES

Infant mortality is a major indicator of the health of a nation. We analyzed recent patterns and trends in U.S. infant mortality, with an emphasis on two of the greatest challenges: (1) persistent racial and ethnic disparities and (2) the impact of preterm and low birthweight delivery.

METHODS

Data from the national linked birth/infant death datasets were used to compute infant mortality rates per 100,000 live births by cause of death (COD), and per 1,000 live births for all other variables. Infant mortality rates and other measures of infant health were analyzed and compared. Leading and preterm-related CODs, and international comparisons of infant mortality rates were also examined.

RESULTS

Despite the rapid decline in infant mortality during the 20th century, the U.S. infant mortality rate did not decline from 2000 to 2005, and declined only marginally in 2006. Racial and ethnic disparities in infant mortality have persisted and increased, as have the percentages of preterm and low birthweight deliveries. After decades of improvement, the infant mortality rate for very low birthweight infants remained unchanged from 2000 to 2005. Infant mortality rates from congenital malformations and sudden infant death syndrome declined; however, rates for preterm-related CODs increased. The U.S. international ranking in infant mortality fell from 12th place in 1960 to 30th place in 2005.

CONCLUSIONS

Infant mortality is a complex and multifactorial problem that has proved resistant to intervention efforts. Continued increases in preterm and low birthweight delivery present major challenges to further improvement in the infant mortality rate.