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

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.

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.

Association Between Temporal Changes in Neonatal Mortality and Spontaneous and Clinician-Initiated Deliveries in the United States, 2006-2013

IMPORTANCE

Preterm and postterm deliveries have declined since 2005 in the United States, but the association between these changes and neonatal mortality remains unknown.

OBJECTIVE

To estimate changes in the gestational age distribution among spontaneous and clinician-initiated deliveries between 2006 and 2013 and associated changes in neonatal mortality.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort analysis was conducted of 22 million singleton live births without major malformations in the United States from 2006 to 2013. Data analysis was performed from August to October 2017.

MAIN OUTCOMES AND MEASURES

Changes in gestational age distribution among spontaneous and clinician-initiated deliveries at extremely preterm (20-27 weeks), very preterm (28-31 weeks), moderately preterm (32-33 weeks), late preterm (34-36 weeks), early term (37-38 weeks), term (39-40), late term (41 weeks), and postterm (42-44 weeks) gestations and changes in neonatal mortality rates at less than 28 days between 2006 and 2013. These changes were estimated from log-linear Poisson regression models with robust variance, adjusted for confounders.

RESULTS

Among 22 million births, 12 493 531 (56.7%) were spontaneous and 9 557 815 (43.3%) were clinician-initiated deliveries. Among spontaneous deliveries, the proportion of births at 20 to 27, 28 to 31, 32 to 33, 34 to 36, and 37 to 38 weeks declined. Among clinician-initiated deliveries, the proportion of births at 34 to 36 and 37 to 38 weeks declined and the proportion at 39 to 40 weeks increased. Among spontaneous deliveries, overall neonatal mortality rates declined from 1.8 to 1.3 per 1000 live births, mainly at 20 to 27 weeks (adjusted annual decline, 1%; 95% CI, -2% to -1%) and 28 to 31 weeks (adjusted annual decline, 6%; 95% CI, -8% to -5%). Among clinician-initiated deliveries, overall mortality rates remained unchanged (2.1 to 2.2 per 1000 live births). However, mortality rates declined (0.6 to 0.5 per 1000 live births) at 39 to 40 weeks by 1% (95% CI, -3% to -0.4%) annually, adjusted for confounders.

CONCLUSIONS AND RELEVANCE

In the United States, there was a decline in spontaneous deliveries associated with an overall decline in neonatal mortality. Although clinician-initiated deliveries increased at 39 to 40 weeks, neonatal mortality at that gestation declined.

Association of Temporal Changes in Gestational Age With Perinatal Mortality in the United States, 2007-2015

Importance

Whether the changing gestational age distribution in the United States since 2005 has affected perinatal mortality remains unknown.

Objective

To examine changes in gestational age distribution and gestational age-specific perinatal mortality.

Design, Setting, and Participants

This retrospective cohort study examined trends in US perinatal mortality by linking live birth and infant death data among more than 35 million singleton births from January 1, 2007, through December 31, 2015.

Exposures

Year of birth and changes in gestational age distribution.

Main Outcomes and Measures

Changes in the proportion of births at gestational ages 20 to 27, 28 to 31, 32 to 33, 34 to 36, 37 to 38, 39 to 40, 41, and 42 to 44 weeks; changes in perinatal mortality (stillbirth at ≥20 weeks, and neonatal deaths at <28 days) rates; and contribution of gestational age changes to perinatal mortality. Trends were estimated from log-linear regression models adjusted for confounders.

Results

Among the 34 236 577 singleton live births during the study period, the proportion of births at all gestational ages declined, except at 39 to 40 weeks, which increased (54.5% in 2007 to 60.2% in 2015). Overall perinatal mortality declined from 9.0 to 8.6 per 1000 births (P < .001). Stillbirths declined from 5.7 to 5.6 per 1000 births (P < .001), and neonatal mortality declined from 3.3 to 3.0 per 1000 births (P < .001). Although the proportion of births at gestational ages 34 to 36, 37 to 38, and 42 to 44 weeks declined, perinatal mortality rates at these gestational ages showed annual adjusted relative increases of 1.0% (95% CI, 0.6%-1.4%), 2.3% (95% CI, 1.9%-2.8%), and 4.2% (95% CI, 1.5%-7.0%), respectively. Neonatal mortality rates at gestational ages 34 to 36 and 37 to 38 weeks showed a relative adjusted annual increase of 0.9% (95% CI, 0.2%-1.6%) and 3.1% (95% CI, 2.1%-4.1%), respectively. Although the proportion of births at gestational age 39 to 40 weeks increased, perinatal mortality showed an annual relative adjusted decline of -1.3% (95% CI, -1.8% to -0.9%). The decline in neonatal mortality rate was largely attributable to changes in the gestational age distribution than to gestational age-specific mortality.

Conclusions and Relevance

Although the proportion of births at gestational age 39 to 40 weeks increased, perinatal mortality at this gestational age declined. This finding may be owing to pregnancies delivered at 39 to 40 weeks that previously would have been unnecessarily delivered earlier, leaving fetuses at higher risk for mortality at other gestational ages.

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.