Variation by state in outcomes classification for deliveries less than 500 g in the United States

County-level Structural Vulnerabilities in Maternal Health and Geographic Variation in Infant Mortality

OBJECTIVE

To evaluate whether community factors that differentially affect the health of pregnant people contribute to geographic differences in infant mortality across the United States.

STUDY DESIGN

This retrospective cohort study sought to characterize the association of a novel composite measure of county-level maternal structural vulnerabilities, the Maternal Vulnerability Index (MVI), with risk of infant death. We evaluated 11,456,232 singleton infants born at 22 0/7 through 44 6/7 weeks' gestation from 2012 to 2014. Using county-level MVI, which ranges from 0-100, multivariable mixed effects logistic regression models quantified associations per 20-point increment in MVI, with odds of death clustered at the county level and adjusted for state, maternal, and infant covariates. Secondary analyses stratified by the social, physical, and health exposures that comprise the overall MVI score. Outcome was also stratified by cause of death.

RESULTS

Odds of death were higher among infants from counties with the greatest maternal vulnerability (0.62% in highest quintile vs 0.32% in lowest quintile, [p<0.001]). Odds of death increased 6% per 20-point increment in MVI (aOR: 1.06, 95% CI 1.04, 1.07). The effect estimate was highest with theme of mental health and substance use (aOR 1.08; 95% CI 1.06, 1.09). Increasing vulnerability was associated with six of seven causes of death.

CONCLUSIONS

Community-level social, physical, and healthcare determinants indicative of maternal vulnerability may explain some of the geographic variation in infant death, regardless of cause of death. Interventions targeted to county-specific maternal vulnerabilities may reduce infant mortality.

National Trends in Preterm Infant Mortality in the United States by Race and Socioeconomic Status, 1995-2020

Importance

Inequalities in preterm infant mortality exist between population subgroups within the United States.

Objective

To characterize trends in preterm infant mortality by maternal race and socioeconomic status to assess how inequalities in preterm mortality rates have changed over time.

Design, Setting, and Participants

This was a retrospective longitudinal descriptive study using the US National Center for Health Statistics birth infant/death data set for 12 256 303 preterm infant births over 26 years, between 1995 and 2020. Data were analyzed from December 2022 to March 2023.

Exposures

Maternal characteristics including race, smoking status, educational attainment, antenatal care, and insurance status were used as reported on an infant's US birth certificate.

Main Outcomes and Measures

Preterm infant mortality rate was calculated for each year from 1995 to 2020 for all subgroups, with a trend regression coefficient calculated to describe the rate of change in preterm mortality.

Results

The average US preterm infant mortality rate (IMR) decreased from 33.71 (95% CI, 33.71 to 34.04) per 1000 preterm births per year between 1995-1997, to 23.32 (95% CI, 23.05 to 23.58) between 2018-2020. Black non-Hispanic infants were more likely to die following preterm births than White non-Hispanic infants (IMR, 31.09; 95% CI, 30.44 to 31.74, vs 21.81; 95% CI, 21.43 to 22.18, in 2018-2020); however, once born, extremely prematurely Black and Hispanic infants had a narrow survival advantage (IMR rate ratio, 0.87; 95% CI, 0.84 to 0.91, in 2018-2020). The rate of decrease in preterm IMR was higher in Black infants (-0.015) than in White (-0.013) and Hispanic infants (-0.010); however, the relative risk of preterm IMR among Black infants compared with White infants remained the same between 1995-1997 vs 2018-2020 (relative risk, 1.40; 95% CI, 1.38 to 1.44, vs 1.43; 95% CI, 1.39 to 1.46). The rate of decrease in preterm IMR was higher in nonsmokers compared with smokers (-0.015 vs -0.010, respectively), in those with high levels of education compared with those with intermediate or low (-0.016 vs - 0.010 or -0.011, respectively), and in those who had received adequate antenatal care compared with those who did not (-0.014 vs -0.012 for intermediate and -0.013 for inadequate antenatal care). Over time, the relative risk of preterm mortality widened within each of these subgroups.

Conclusions and Relevance

This study found that between 1995 and 2020, US preterm infant mortality improved among all categories of prematurity. Inequalities in preterm infant mortality based on maternal race and ethnicity have remained constant while socioeconomic disparities have widened over time.

Assisted Reproductive Technology and Perinatal Mortality: Selected States (2006-2011)

OBJECTIVE

This study aimed to compare trends and characteristics of assisted reproductive technology (ART) and non-ART perinatal deaths and to evaluate the association of perinatal mortality and method of conception (ART vs. non-ART) among ART and non-ART deliveries in Florida, Massachusetts, and Michigan from 2006 to 2011.

STUDY DESIGN

Retrospective cohort study using linked ART surveillance and vital records data from Florida, Massachusetts, and Michigan.

RESULTS

During 2006 to 2011, a total of 570 ART-conceived perinatal deaths and 25,158 non-ART conceived perinatal deaths were identified from the participating states. Overall, ART perinatal mortality rates were lower than non-ART perinatal mortality rates for both singletons (7.0/1,000 births vs. 10.2/1,000 births) and multiples (22.8/1,000 births vs. 41.2/1,000 births). At <28 weeks of gestation, the risk of perinatal death among ART singletons was significantly lower than non-ART singletons (adjusted risk ratio [aRR] = 0.46, 95% confidence interval [CI]: 0.26-0.85). Similar results were observed among multiples at <28 weeks of gestation (aRR = 0.64, 95% CI: 0.45-0.89).

CONCLUSION

Our findings suggest that ART use is associated with a decreased risk of perinatal deaths prior to 28 weeks of gestation, which may be explained by earlier detection and management of fetal and maternal conditions among ART-conceived pregnancies. These findings provide valuable information for health care providers, including infertility specialists, obstetricians, and pediatricians when counseling ART users on risk of treatment.

KEY POINTS

· ART use is associated with a decreased risk of perinatal deaths prior to 28 weeks of gestation.. · ART perinatal mortality rates were lower than that for non-ART perinatal mortality.. · This study used linked data to examine associations between use of ART and perinatal deaths..

Regional Contribution of Previable Infant Deaths to Infant Mortality Rates in the United States

OBJECTIVE

Lack of standardization of infant mortality rate (IMR) calculation between regions in the United States makes comparisons potentially biased. This study aimed to quantify differences in the contribution of early previable live births (<20 weeks) to U.S. regional IMR.

STUDY DESIGN

Population-based cohort study of all U.S. live births and infant deaths recorded between 2007 and 2014 using Centers for Disease Control and Prevention's (CDC's) WONDER database linked birth/infant death records (births from 17-47 weeks). Proportion of infant deaths attributable to births <20 vs. 20 to 47 weeks, and difference (ΔIMR) between reported and modified (births ≥20 weeks) IMRs were compared across four U.S. census regions (North, South, Midwest, and West).

RESULTS

Percentages of infant deaths attributable to birth <20 weeks were 6.3, 6.3, 5.3, and 4.1% of total deaths for Northeast, Midwest, South, and West, respectively, p < 0.001. Contribution of < 20-week deaths to each region's IMR was 0.34, 0.42, 0.37, and 0.2 per 1,000 live births. Modified IMR yielded less regional variation with IMRs of 5.1, 6.2, 6.6, and 4.9 per 1,000 live births.

CONCLUSION

Live births at <20 weeks contribute significantly to IMR as all result in infant death. Standardization of gestational age cut-off results in more consistent IMRs among U.S. regions and would result in U.S. IMR rates exceeding the healthy people 2020 goal of 6.0 per 1,000 live births.

Prematurity and race account for much of the interstate variation in infant mortality rates in the United States

OBJECTIVE

To assess the correlation between infant mortality and extreme prematurity by state.

STUDY DESIGN

This ecological study included data on 28,526,534 infants from 2007 to 2013 in all 50 US states and DC using CDC WONDER linked birth and infant death records. Regression analyses determined the correlation between infant and neonatal mortality rates and the proportion of extremely preterm, extremely low birth weight, and black births by state.

RESULTS

State infant and neonatal mortality rates were directly and highly correlated with the proportion of extremely preterm births (infant, r² = 0.71, P < 0.001; neonatal, r² = 0.77, P < 0.001) and extremely low birth weight births (r² = 0.63, P < 0.001; r² = 0.73, P < 0.001). The proportion of black births also correlated directly with infant and neonatal mortality rates.

CONCLUSIONS

Interstate variation in infant and neonatal mortality rates are primarily driven by rates of extremely preterm and extremely low birth weight births which is closely related to the proportion of black births.

Regional and practitioner variations in reporting infant mortality

Objective: Assess regional differences in categorization of preterm delivery outcomes and impact on variation in reported infant mortality rates.Study design: A 27-item questionnaire was distributed to 1072 practitioners associated with U.S. birth hospitals. Five clinical scenarios were created to identify how participants classify delivery outcomes. Statistical analysis included Chi-square analysis and multinomial logistic regression.Results: 234 questionnaires were completed (response rate 22%). While >90% respondents classified a 14-week pregnancy loss with no sign of life as a miscarriage, only 22% would provide a fetal death certificate. Likewise, 37% would provide a certificate of live birth for a loss at 16 weeks with signs of life. There was notable regional variation in classifying these as live births (Northeast: 41%, Midwest: 44%, South: 13%, and West: 18%, p = .003).Conclusion: Regional practice variation in recording both live births and stillbirths was noted. Greater standardization in reporting practices may be warranted to improve the accuracy of reported birth outcomes in the U.S.

A new record linkage for assessing infant mortality rates in Ontario, Canada

OBJECTIVE

Infant mortality statistics for Canada have routinely omitted Ontario-Canada's most populous province-as a high proportion of Vital Statistics infant death registrations could not be linked with their corresponding Vital Statistics live birth registrations. We assessed the feasibility of linking an alternative source of live birth information with infant death registrations.

METHODS

All infant deaths occurring before 365 days of age registered in Ontario's Vital Statistics in 2010-2011 were linked with birth records in the Canadian Institute for Health Information's hospitalization database. Crude birthweight-specific and gestational age-specific infant mortality rates were calculated, and rates examined according to maternal and infant characteristics.

RESULTS

Of 1311 infant death registrations, only 47 (3.6%) could not be linked to a hospital birth record. The overall crude infant mortality rate was 4.7 deaths per 1000 live births (95% CI, 4.4 to 4.9), the same as previously reported for the rest of Canada in 2011. Infant mortality was higher in women < 20 years (5.8 per 1000 live births) and ≥ 40 years (5.9 per 1000 live births), and lowest among those aged 25-29 years (3.9 per 1000 live births). Infant mortality was notably higher in the lowest (5.1 per 1000 live births) residential income quintile than the highest (3.4 per 1000 live births).

CONCLUSION

Use of birth hospitalization records resulted in near-complete linkage of all Vital Statistics infant death registrations. This approach could enhance the conduct of representative surveillance and research on infant mortality when direct linkage of live birth and infant death registrations is not achievable.

The Effect of Technology-Based Programmes on Changing Health Behaviours of Adolescents: Systematic Review

Technology-based applications in the health field have been increasing in recent years. Since they attract adolescents' attention, technology-based applications can be used in health-promoting interventions. This systematic literature review was conducted to determine the effect of technology-based programmes in changing adolescent health behaviors. In the literature review, 16 randomized controlled empirical studies with full text published in English between 2011 and 2016 in the PubMed and Science Direct databases were investigated. The sample of the studies investigated under the scope of this study consisted of adolescents in the age range of 12-24 years. The intervention time was determined to be a minimum of two weeks and a maximum of 24 months. When the resulting studies were examined, the model was used in some of the studies. The intervention methods used for adolescents were generally presented as informing, counseling services, protection, behavioral change development, self-assessment, goal development and problem-solving. It was observed that the majority of the studies were Internet and computer-based, and some were mobile phone-based. In 56.25% of the studies, the development in the studied health behaviors was found to be significant. In addition, 62.5% of the adolescents stated that they were satisfied with technology-based programmes. In the studies, some of the difficulties in the use of technology included the participants' withdrawing from the research, their having difficulties in accessing the website, and other technical problems. The use of technology in health promotion is becoming widespread, especially among adolescents, which increases the success of behavioural change. However, further randomized controlled studies are needed in the field to increase evidence-based knowledge.

Outcomes of Extremely Preterm Infants With Birth Weight Less Than 400 g

IMPORTANCE

Birth weight (BW) is an important predictor of mortality and morbidity. At extremely early gestational ages (GAs), BW may influence decisions regarding initiation of resuscitation.

OBJECTIVE

To characterize outcomes of liveborn infants with a BW less than 400 g.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective multicenter cohort study analyzed extremely preterm infants born between January 2008 and December 2016 within the National Institute of Child Health and Human Development Neonatal Research Network. Infants with a BW less than 400 g and a GA of 22 to 26 weeks were included. Active treatment was defined as the provision of any potentially lifesaving intervention after birth. Survival was analyzed for the entire cohort; neurodevelopmental impairment (NDI) was examined for those born between January 2008 and December 2015 (birth years with outcomes available for analysis). Neurodevelopmental impairment at 18 to 26 months' corrected age (CA) was defined as a Bayley Scales of Infant and Toddler Development, Third Edition, cognitive composite score less than 85, a motor composite score less than 85, moderate or severe cerebral palsy, gross motor function classification system score of 2 or greater, bilateral blindness, and/or hearing impairment. Data were analyzed from September 2017 to October 2018.

EXPOSURES

Birth weight less than 400 g.

MAIN OUTCOMES AND MEASURES

The primary outcome was survival to discharge among infants who received active treatment. Analysis of follow-up data was limited to infants born from 2008 to 2015 to ensure children had reached assessment age. Within this cohort, neurodevelopmental outcomes were assessed for infants who survived to 18 to 26 months' CA and returned for a comprehensive visit.

RESULTS

Of the 205 included infants, 121 (59.0%) were female, 133 (64.9%) were singletons, and 178 (86.8%) were small for gestational age. Almost half (101 of 205 [49.3%]) received active treatment at birth. A total of 26 of 205 infants (12.7%; 95% CI, 8.5-18.9) overall survived to discharge, and 26 of 101 actively treated infants (25.7%; 95% CI, 17.6-35.4) survived to discharge. Within the subset of infants with a BW less than 400 g and a GA of 22 to 23 weeks, 6 of 36 actively treated infants (17%; 95% CI, 6-33) survived to discharge. Among infants born between 2008 and 2015, 23 of 90 actively treated infants (26%; 95% CI, 17-36) survived to discharge. Two infants died after discharge, and 2 were lost to follow-up. Thus, 19 of 90 actively treated infants (21%; 95% CI, 13-31) were evaluated at 18 to 26 months' CA. Moderate or severe NDI occurred in 14 of 19 infants (74%).

CONCLUSIONS AND RELEVANCE

Infants born with a BW less than 400 g are at high risk of mortality and significant morbidity. Although 21% of infants survived to 18 to 26 months' CA with active treatment, NDI was common among survivors.

Comparing regional neonatal mortality rates: the influence of registration of births as live born for birth weight <500 g in Taiwan

OBJECTIVE

To investigate regional variation in the registration of births (still+live) as live born for birth weight <500 g and the impact on the city/county ranking of neonatal mortality rate (NMR) in Taiwan.

DESIGN

Population-based cross-sectional ecological study.

SETTING

20 cities/counties in Taiwan.

PARTICIPANTS

Registered births for birth weight <500 g and neonatal deaths in 2015-2016.

MAIN OUTCOME MEASURES

City/county percentage of births <500 g registered as live born and ranking of city/county NMR (deaths per 1000 live births) including and excluding live births <500 g.

RESULTS

The percentage of births <500 g registered as live born ranged from 0% in Keelung City (0/26) and Penghu County (0/4) to 20% in Taipei City (112/558), 24% in Hsinchu County (5/21) and 28% in Hualien County (9/32). The change in city/county ranking of NMR from including to excluding live births <500 g was most prominent in Taipei City (from the 15th to the 1st) followed by Kaohsiung City (from the 18th to the 14th).

CONCLUSIONS

The city/county NMR in Taiwan is influenced by variation in the registration of live born for births with uncertain viability. We recommend presenting city/county NMR using both criteria (with or without minimum threshold of gestation period or birth weight) for better interpretation of the findings of comparisons of city/county NMR.

The Collaborative Improvement and Innovation Network (CoIIN) to Reduce Infant Mortality: An Outcome Evaluation From the US South, 2011 to 2014

OBJECTIVES

To evaluate the impact of the Southern Public Health Regions' (Regions IV and IV) Collaborative Improvement and Innovation Network (CoIIN) to Reduce Infant Mortality, supported by the US Health Resources and Services Administration.

METHODS

We examined pre-post change (2011-2014) for CoIIN strategies with available outcome data from vital records (early elective delivery, smoking) and the Pregnancy Risk Assessment Monitoring System (safe sleep) as well as preterm birth and infant mortality for Regions IV and VI relative to all other regions.

RESULTS

For most outcomes, CoIIN improvements were greater in Regions IV and VI than in other regions. For example, early elective delivery decreased by 22% versus 14% in other regions, smoking cessation during pregnancy increased by 7% versus 2%, and back sleep position increased by 5% versus 2%. Preterm birth decreased by 4%, twice that observed in other regions, but infant mortality reductions did not differ significantly.

CONCLUSIONS

The CoIIN approach to public health improvement shows promise in accelerating progress in intermediate outcomes and preterm birth. Impact on infant mortality may require additional strategies and sustained efforts.

Geographic Accessibility to Health Services and Neonatal Mortality Among Very-Low Birthweight Infants in South Carolina

Introduction Mortality for infants born with very-low birthweight (VLBW, 500-1499 grams) is markedly higher than for babies born with normal birthweight (2500-4000 grams). Although these high-risk infants show better outcomes in advanced care settings, only 80 % of VLBW infants born in South Carolina (SC) are delivered in hospitals with a level-III neonatal intensive care unit (NICU). The purpose of this research project was to assess geographic access to delivery hospitals and risk of neonatal death among singleton VLBW infants born in SC. Methods The linked birth and death records of a cross-sectional, population-based study of singleton VLBW infants born in SC between 2010 and 2012 were used (n = 2030). We assessed the impact of travel time from maternal residence to delivery hospital. Logistic regression modeling was performed with adjustments for maternal, newborn, and hospital characteristics. Results The neonatal mortality rate among singleton VLBW infants was 11.03 deaths per 100 live births in 2010-2012. We did not find a significant association between travel time to delivery hospital and neonatal mortality after adjusting for confounders. However, we found that a 1-week increase in gestational age (odds ratio (OR): 0.61) and non-Hispanic black mothers (versus non-Hispanic white mothers) (OR: 0.68) were associated with lower odds of neonatal death, whereas non-NICU admission at birth (OR: 5.90) was associated with increased odds of death. The results of the sensitivity analyses including both singleton and multiple births did not yield significant results for travel time and neonatal mortality in VLBW infants. Discussion Although we found no significant association between travel time and neonatal mortality in singleton VLBW births in SC, we identified significant factors consistent with those found in previous studies that may affect neonatal mortality.

Disparities in gestational age-specific fetal mortality rates in the United States, 2009-2013

PURPOSE

Although studies have examined overall temporal changes in gestational age-specific fetal mortality rates, there is little information on the current status of racial/ethnic differences. We hypothesize that differences exist between racial/ethnic groups across gestational age and that these differences are not equally distributed.

METHODS

Using the 2009-2013 data from US fetal death and live birth files for non-Hispanic white (NHW); non-Hispanic black (NHB); Hispanic; and American Indian/Alaska Native (AIAN) women, we conducted analyses to examine fetal mortality rates and estimate adjusted prevalence rate ratios and 95% confidence intervals (CIs).

RESULTS

There were lower risks of fetal mortality among NHB women (aPRR = 0.76; 95% CI = 0.71-0.81) and Hispanic women (aPRR = 0.89; 95% CI = 0.83-0.96) compared with NHWs at 22-23 weeks' gestation. For NHB women, the risk was higher starting at 32-33 weeks (aPRR = 1.11; 95% CI = 1.04-1.18) and continued to increase as gestational age increased. Hispanic and AIAN women had lower risks of fetal mortality compared with NHW women until 38-39 weeks.

CONCLUSIONS

Further examination is needed to identify causes of fetal death within the later pregnancy period and how those causes and their antecedents might differ by race and ethnicity.

County-level Variation in Infant Mortality Reporting at Early Previable Gestational Ages

BACKGROUND

Infant mortality rate (IMR), or number of infant deaths per 1000 livebirths, varies widely across the US While fetal deaths are not included in this measure, reported infant deaths do include those delivered at previable gestations, or ≤20 weeks gestation. Variation in reporting of these events may have a significant impact on IMR estimates.

METHODS

This retrospective analysis used US National Center for Health Statistics 2007-2013 data from 2391 US counties. Counties were categorised by US region, demographic characteristics, and state-level fetal death reporting requirements. County percentage of fetal deaths among all 17-20 week fetal and infant deaths was evaluated using multivariable linear regression. County-level characteristics were then included in multivariable linear regression to determine the associated change in county IMR.

RESULTS

County percentage of deaths at 17-20 weeks reported as fetal ranged from 0% to 100% (mean 63.7%). Every 1 point increase in this percentage was associated with a 0.02 point decrease in county IMR (95% confidence interval (CI) 0.02, 0.03). When county IMRs were recalculated holding the percentage of fetal vs. infant deaths at 17-20 weeks constant at 63.7%, results suggest that the predicted gap in county IMR between Northeast and Midwest regions would narrow by 0.45 points.

CONCLUSIONS

Variable reporting of previable fetal and infant deaths may compromise the validity of county IMR comparisons. Improved consistency and accuracy of fetal and infant death reporting is warranted.

Methodological Challenges in International Comparisons of Perinatal Mortality

PURPOSE OF REVIEW

Several prestigious agencies routinely rank countries based on crude perinatal and infant mortality rates, while more recently, international neonatal networks have begun comparing neonatal mortality and morbidity rates among very preterm and very low-birth-weight infants. We discuss the methodologic challenges that compromise such comparisons and potential remedies.

RECENT FINDINGS

Crude perinatal mortality rates are biased by international variations in birth registration, especially at the borderline of viability. Such bias is demonstrated by significant differences in crude versus birth weight- and gestational age-specific comparisons of perinatal mortality. Comparisons of neonatal mortality among very preterm and very low-birth-weight infants are plagued by incorrect denominators, and this leads to paradoxical findings.

SUMMARY

A lack of standardization with regard to birth registration and inadequate appreciation of the methods for calculating gestational age-specific mortality rates are responsible for biasing international comparisons of perinatal mortality.

Epidemiology of Periviable Births: The Impact and Neonatal Outcomes of Twin Pregnancy

This article discusses a study that estimated the prevalence of twin live births in the United States that were delivered in the periviable (20-25 weeks) gestational age, and compared changes in twin neonatal mortality and morbidity rates between 2005 and 2013 overall, and at periviable gestations. Although the decline in twin neonatal mortality rates at 23 and 24 weeks is encouraging, and suggests advancement in the neonatal care of these extremely small twins, the concomitant increase in neonatal morbidity at 23 weeks is concerning. Efforts to understand if twins delivered at periviable gestations suffer from long-term consequences of neurodevelopmental and cognitive deficits remain important.

State-Level Progress in Reducing the Black-White Infant Mortality Gap, United States, 1999-2013

OBJECTIVES

To assess state-level progress on eliminating racial disparities in infant mortality.

METHODS

Using linked infant birth-death files from 1999 to 2013, we calculated state-level 3-year rolling average infant mortality rates (IMRs) and Black-White IMR ratios. We also calculated percentage improvement and a projected year for achieving equality if current trend lines are sustained.

RESULTS

We found substantial state-level variation in Black IMRs (range = 6.6-13.8) and Black-White rate ratios (1.5-2.7), and also in percentage relative improvement in IMR (range = 2.7% to 36.5% improvement) and in Black-White rate ratios (from 11.7% relative worsening to 24.0% improvement). Thirteen states achieved statistically significant reductions in Black-White IMR disparities. Eliminating the Black-White IMR gap would have saved 64 876 babies during these 15 years. Eighteen states would achieve IMR racial equality by the year 2050 if current trends are sustained.

CONCLUSIONS

States are achieving varying levels of progress in reducing Black infant mortality and Black-White IMR disparities. Public Health Implications. Racial equality in infant survival is achievable, but will require shifting our focus to determinants of progress and strategies for success.

Abortion and Infant Mortality on the First Day of Life

BACKGROUND

Fetal imaging for congenital anomalies increases pregnancy terminations late in gestation.

OBJECTIVES

We assessed whether late-pregnancy terminations can accidentally result in live births, and how these births impact infant mortality rates over time.

METHODS

We carried out a population-level analysis of 12,141 infant deaths in Quebec, Canada from 1986 to 2012. We calculated the proportion of infants born alive who died following pregnancy termination. The exposure was pregnancy termination with or without congenital anomaly recorded on death certificates. The main outcome was mortality on the first day of life by the hour.

RESULTS

Pregnancy termination was the cause of 19.4 infant deaths per 100,000 in 2000-2012, compared with 1.0 per 100,000 in 1986-1999. Most deaths after termination occurred in the first 3 h of life among infants with anomalies who weighed <500 g. In 2000-2012, infants who died following pregnancy termination led to an excess of 0.2 deaths per 1,000 on the first day of life, i.e. an 8.6% increase in the infant mortality rate (p value = 0.002).

CONCLUSIONS

Pregnancy termination in mid-gestation carries the risk of accidental live birth. These neonates increasingly affect infant mortality rates. Better recording is needed, including data on the prevention and management of accidental live births after pregnancy termination.

Differences in perinatal and infant mortality in high-income countries: artifacts of birth registration or evidence of true differences?

Background

Variation in birth registration criteria may compromise international comparisons of fetal and infant mortality. We examined the effect of birth registration practices on fetal and infant mortality rates to determine whether observed differences in perinatal and infant mortality rates were artifacts of birth registration or reflected true differences in health status.

Methods

A retrospective population-based cohort study was done using data from Canada, United States, Denmark, Finland, Iceland, Norway, and Sweden from 1995–2005. Main outcome measures included live births by gestational age and birth weight; gestational age—and birth weight-specific stillbirth rates; neonatal, post-neonatal, and cause-specific infant mortality.

Results

Proportion of live births <22 weeks varied substantially: Sweden (not reported), Iceland (0.00 %), Finland (0.001 %), Denmark (0.01 %), Norway (0.02 %), Canada (0.07 %) and United States (0.08 %). At 22–23 weeks, neonatal mortality rates were highest in Canada (892.2 per 1000 live births), Denmark (879.3) and Iceland (1000.0), moderately high in the United States (724.1), Finland (794.3) and Norway (739.0) and low in Sweden (561.2). Stillbirth:live birth ratios at 22–23 weeks were significantly lower in the United States (79.2 stillbirths per 100 live births) and Finland (90.8) than in Canada (112.1), Iceland (176.2) and Norway (173.9). Crude neonatal mortality rates were 83 % higher in Canada and 96 % higher in the United States than Finland. Neonatal mortality rates among live births ≥28 weeks were lower in Canada and United States compared with Finland. Post-neonatal mortality rates were higher in Canada and United States than in Nordic countries.

Conclusions

Live birth frequencies and stillbirth and neonatal mortality patterns at the borderline of viability are likely due to differences in birth registration practices, although true differences in maternal, fetal and infant health cannot be ruled out. This study emphasises the need for further standardisations, in order to enhance the relevance of international comparisons of infant mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0430-8) contains supplementary material, which is available to authorized users.

Variation in classification of live birth with newborn period death versus fetal death at the local level may impact reported infant mortality rate

BACKGROUND

To better understand factors that may impact infant mortality rates (IMR), we evaluated the consistency across birth hospitals in the classification of a birth event as either a fetal death or an early neonatal (infant) death using natality data from North Carolina for the years 1995-2000.

METHODS

A database consisting of fetal deaths and infant deaths occurring within the first 24 hours after birth was constructed. Bivariate, followed by multivariable regression, analyses were used to control for relevant maternal and infant factors. Based upon hospital variances, adjustments were made to evaluate the impact of the classification on statewide infant mortality rate.

RESULTS

After controlling for multiple maternal and infant factors, birth hospital remained a factor related to the classification of early neonatal versus fetal death. Reporting of early neonatal deaths versus fetal deaths consistent with the lowest or highest hospital strata would have resulted in an adjusted IMR varying from 7.5 to 10.64 compared with the actual rate of 8.95.

CONCLUSIONS

Valid comparisons of IMR among geographic regions within and between countries require consistent classification of perinatal deaths. This study demonstrates that local variation in categorization of death events as fetal death versus neonatal death within the first 24 hours after delivery may impact a state-level IMR in a meaningful magnitude. The potential impact of this issue on IMRs should be examined in other state and national populations.

Long-term outcome for the tiniest or most immature babies: survival rates

This article focuses on the survival rates of the most immature babies considered viable from around the world. It discusses the various factors in terms of definition, inclusion criteria and policy which can result in marked differences in the apparent rates of delivery (all births), live birth, admission to neonatal intensive care and ultimately survival seen between otherwise similar countries, different regions of the same country, and even adjacent hospitals. Such variation in approach can result in major differences in reported survival and consequentially have large effects on apparent rates of adverse long-term outcome.

Contributors to excess infant mortality in the U.S. South

BACKGROUND

Infant mortality rates (IMRs) are disproportionally high in the U.S. South; however, the proximate contributors that could inform regional action remain unclear.

PURPOSE

To quantify the components of excess infant mortality in the U.S. South by maternal race/ethnicity, underlying cause of death, and gestational age.

METHODS

U.S. Period Linked Birth/Infant Death Data Files 2007-2009 (analyzed in 2013) were used to compare IMRs between the South (U.S. Public Health Regions IV and VI) and all other regions combined.

RESULTS

Compared to other regions, there were 1.18 excess infant deaths per 1000 live births in the South, representing about 1600 excess infant deaths annually. New Mexico and Texas did not have elevated IMRs relative to other regions; excess death rates among other states ranged from 0.62 per 1000 in Kentucky to 3.82 per 1000 in Mississippi. Racial/ethnic compositional differences, generally the greater proportion of non-Hispanic black births in the South, explained 59% of the overall regional difference; the remainder was mostly explained by higher IMRs among non-Hispanic whites. The leading causes of excess Southern infant mortality were sudden unexpected infant death (SUID; 36%, range=12% in Florida to 90% in Kentucky) and preterm-related death (22%, range= -71% in Kentucky to 51% in North Carolina). Higher rates of preterm birth, predominantly <34 weeks, accounted for most of the preterm contribution.

CONCLUSIONS

To reduce excess Southern infant mortality, comprehensive strategies addressing SUID and preterm birth prevention for both non-Hispanic black and white births are needed, with state-level findings used to tailor state-specific efforts.

Extremely low birth weight and infant mortality rates in the United States

OBJECTIVE

Infant mortality rates (IMR) and neonatal mortality rates (NMR) in the United States have not decreased recently. The purpose of this study was to determine the contributions of birth weight and gestational age subgroups to the IMR and NMR in the United States.

METHODS

We used the most recent (1983-2005) US linked birth and infant death data and simple regression analysis to determine the contributions of specific birth weight and gestational age subgroups to trends in IMR and NMR.

RESULTS

IMR and NMR decreased between 1983 and 2005 for all birth weight and gestational age subgroups. There was an increase in births of very low birth weight infants from 1.2% to 1.5% (P < .001) over this period. The proportion of very low birth weight-infant deaths increased from 42.9% to 54.8%, resulting in recent nonsignificant declines in IMR and NMR. The proportion of live-birth infants <500 g increased from 0.12% to 0.18% (P < .001). The adjusted IMR and NMR over time (excluding infants <500 g) have steeper declining trends than the ones including infants <500 g. The changes in overall IMR and NMR in recent years (2000-2005) are not statistically significant. However, the adjusted IMR and NMR trends during this time are highly significant.

CONCLUSIONS

The increased proportions of infants <500 g and other low birth weight infants contribute greatly to the lack of a decrease in IMR and NMR from 2000 to 2005, although birth weight- and gestational age-specific IMR and NMR continue to decrease.

Comparing regional infant death rates: the influence of preterm births <24 weeks of gestation

OBJECTIVE

To investigate regional variation in the registration of preterm births <24 weeks of gestation and the impact on infant death rates for English Primary Care Trusts (PCTs).

DESIGN

Cohort study.

SETTING

England.

PARTICIPANTS

All registered births (1 January 2005-31 December 2008) by gestational age and PCT (147 trusts) linked to infant deaths (up to 1 year of life). Late-fetal deaths at 22 and 23 weeks gestation (1 January 2005-31 December 2006).

MAIN OUTCOME MEASURES

Extremely preterm (<24 weeks) birth rate per 1000 live births and percentage of births registered as live born by PCT. Infant death rate and rank of mortality for (1) all live births and (2) live births over 24 weeks gestation by PCT.

RESULTS

Wide between-PCT variation existed in extremely preterm birth (<24 weeks) rates (per 1000 births) (90% central range (0.31, 1.91)) and percentages of births <24 weeks of gestation registered as live born (median 52.6%, 90% central range (26.3%, 79.5%)). Consequently, the percentage of infant deaths arising from these births varied (90% central range (6.7%, 31.9%)). Excluding births <24 weeks, led to significant changes in infant mortality rankings of PCTs, with a median worsening of 12 places for PCTs with low rates of live born preterm births <24 weeks of gestation compared with a median improvement of four ranks for those with higher live birth registration rates.

CONCLUSIONS

Infant death rates in PCTs in England are influenced by variation in the registration of births where viability is uncertain. It is vital that this variation is minimised before infant mortality is used as indicator for monitoring health and performance and targeting interventions.

Developing a standard approach to examine infant mortality: findings from the State Infant Mortality Collaborative (SIMC)

States can improve pregnancy outcomes by using a standard approach to assess infant mortality. The State Infant Mortality Collaborative (SIMC) developed a series of analyses to describe infant mortality in states, identify contributing factors to infant death, and develop the evidence base for implementing new or modifying existing programs and policies addressing infant mortality. The SIMC was conducted between 2004 and 2006 among five states: Delaware, Hawaii, Louisiana, Missouri, and North Carolina. States used analytic strategies in an iterative process to investigate contributors to infant mortality. Analyses were conducted within three domains: data reporting (quality, reporting, definitional criteria, and timeliness), cause and timing of infant death (classification of cause and fetal, neonatal, and postneonatal timing), and maturity and weight at birth/maturity and birth weight-specific mortality. All states identified the SIMC analyses as useful for examining infant mortality trends. In each of the three domains, SIMC results were used to identify important direct contributors to infant mortality including disparities, design or implement interventions to reduce infant death, and identify foci for additional analyses. While each state has unique structural, political, and programmatic circumstances, the SIMC model provides a systematic approach to investigating increasing or static infant mortality rates that can be easily replicated in all other states and allows for cross-state comparison of results.

Disentangling the effects of risk factors and clinical care on subnational variation in early neonatal mortality in the United States

OBJECTIVE

Between 1990 and 2010, the U.S ranking in neonatal mortality slipped from 29(th) to 45(th) among countries globally. Substantial subnational variation in newborn mortality also exists. Our objective is to measure the extent to which trends and subnational variation in early neonatal mortality reflect differences in the prevalence of risk factors (gestational age and birth weight) compared to differences in clinical care.

METHODS

Observational study using linked birth and death data for all births in the United States between 1996 and 2006. We examined health service area (HSA) level variation in the expected early neonatal mortality rate, based on gestational age (GA) and birth-weight (BW), and GA-BW adjusted mortality as a proxy for clinical care. We analyzed the relationship between selected health system indicators and GA-BW-adjusted mortality.

RESULTS

The early neonatal death (ENND) rate declined 12% between 1996 and 2006 (2.39 to 2.10 per 1000 live births). This occurred despite increases in risk factor prevalence. There was significant HSA-level variation in the expected ENND rate (Rate Ratio: 0.73-1.47) and the GA-BW adjusted rate (Rate ratio: 0.63-1.68). Accounting for preterm volume (defined as <34 weeks), the number of neonatologist and NICU beds, 25.2% and 58.7% of the HSA-level variance in outcomes was explained among all births and very low birth weight babies, respectively.

CONCLUSION

Improvements in mortality could be realized through the expansion or reallocation of clinical neonatal resources, particularly in HSAs with a high volume of preterm births; however, prevention of preterm births and low-birth weight babies has a greater potential to improve newborn survival in the United States.

Racial/ethnic differences in infant mortality attributable to birth defects by gestational age

OBJECTIVE

Birth defects are a leading cause of infant mortality in the United States. Previous reports have highlighted black-white differences in overall infant mortality and infant mortality attributable to birth defects (IMBD). We evaluated the impact of gestational age on US racial/ethnic differences in IMBD.

METHODS

We estimated the rate of IMBD as the underlying cause of death using the period-linked birth/infant death data for US residents for January 2003 to December 2006. We excluded infants with missing gestational age, implausible values based on Alexander's index of birth weight for gestational age norms, or gestational ages <20 weeks or >44 weeks; we categorized gestational age into 3 groups: 20 to 33, 34 to 36, and 37 to 44 weeks. Using Poisson regression, we compared neonatal and postneonatal IMBD for infants of non-Hispanic black and Hispanic mothers with that for infants of non-Hispanic white mothers stratified by gestational age.

RESULTS

IMBD occurred in 12.2 per 10 000 live births. Among infants delivered at 37 to 44 weeks, blacks (and Hispanics, to a lesser degree) had significantly higher neonatal and postneonatal IMBD than whites; however, among infants delivered at 20 to 33 or 34 to 36 weeks, neonatal (but not postneonatal) IMBD was significantly lower among blacks compared with whites.

CONCLUSIONS

Racial/ethnic differences in IMBD were not explained in these data by differences in gestational age. Further investigation should include an assessment of possible racial/ethnic differences in severity and/or access to timely diagnosis and management of birth defects.

Impact of fetal death reporting requirements on early neonatal and fetal mortality rates and racial disparities

OBJECTIVE

Racial disparities in infant and neonatal mortality vary substantially across the U.S. with some states experiencing wider disparities than others. Many factors are thought to contribute to these disparities, but state differences in fetal death reporting have received little attention. We examined whether such reporting requirements may explain national variation in neonatal and fetal mortality rates and racial disparities.

METHODS

We used data on non-Hispanic white and non-Hispanic black infants from the U.S. 2000-2002 linked birth/infant death and fetal death records to determine the degree to which state fetal death reporting requirements explain national variation in neonatal and fetal mortality rates and racial disparities. States were grouped depending upon whether they based the lower limit for fetal death reporting on birthweight alone, gestational age alone, both birthweight and gestational age, or required reporting of all fetal deaths. Traditional methods and the fetuses-at-risk approach were used to calculate mortality rates, 95% confidence intervals, and relative and absolute racial disparity measures in these four groups.

RESULTS

States with birthweight-alone fetal death thresholds substantially underreported fetal deaths at lower gestations and slightly overreported neonatal deaths at older gestations. This finding was reflected by these states having the highest neonatal mortality rates and disparities, but the lowest fetal mortality rates and disparities.

CONCLUSIONS

Using birthweight alone as a reporting threshold may promote some shift of fetal deaths to newborn deaths, contributing to racial disparities in neonatal mortality. The adoption of a uniform national threshold for reporting fetal deaths could reduce systematic differences in live birth and fetal death reporting.

Influence of definition based versus pragmatic birth registration on international comparisons of perinatal and infant mortality: population based retrospective study

OBJECTIVES

To examine variations in the registration of extremely low birthweight and early gestation births and to assess their effect on perinatal and infant mortality rankings of industrialised countries.

DESIGN

Retrospective population based study.

SETTING

Australia, Canada, European countries, and the United States for 2004; Australia, Canada, and New Zealand for 2007.

POPULATION

National data on live births and on fetal, neonatal, and infant deaths.

MAIN OUTCOME MEASURES

Reported proportions of live births with birth weight/gestational age of less than 500 g, less than 1000 g, less than 24 weeks, and less than 28 weeks; crude rates of fetal, neonatal, and infant mortality; mortality rates calculated after exclusion of births under 500 g, under 1000 g, less than 24 weeks, and less than 28 weeks.

RESULTS

The proportion of live births under 500 g varied widely from less than 1 per 10,000 live births in Belgium and Ireland to 10.8 per 10,000 live births in Canada and 16.9 in the United States. Neonatal deaths under 500 g, as a proportion of all neonatal deaths, also ranged from less than 1% in countries such as Luxembourg and Malta to 29.6% in Canada and 31.1% in the United States. Rankings of countries based on crude fetal, neonatal, and infant mortality rates differed substantially from rankings based on rates calculated after exclusion of births with a birth weight of less than 1000 g or a gestational age of less than 28 weeks.

CONCLUSIONS

International differences in reported rates of extremely low birthweight and very early gestation births probably reflect variations in registration of births and compromise the validity of international rankings of perinatal and infant mortality.