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State Infant Mortality Toolkit. Workshop: Investigating High or Increased Infant Mortality Rates. Session Leaders:. Danielle Sollers—AMCHP William Sappenfield—CDC Greg Alexander—USF. 11 th Annual MCH EPI Conference Miami, FL – Dec. 10, 2005.
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State Infant Mortality Toolkit Workshop:Investigating High or Increased Infant Mortality Rates Session Leaders: Danielle Sollers—AMCHP William Sappenfield—CDC Greg Alexander—USF 11th Annual MCH EPI Conference Miami, FL – Dec. 10, 2005
State Infant Mortality Toolkit Workshop • Background on SIMC • SIMC Toolkit Overview, Framework, and Next Steps • Stage 1 Framework Components • Maturation • Maturation-specific mortality • Age and Cause of Death • Vital Records Reporting
Toolkit Framework State Infant Mortality Toolkit Stage 1 – Overview Investigation Stage 2 – Focused Investigation
Toolkit Framework Stage 1 – Overview Investigation Maturation-Specific Maturation Data Reporting Age & Cause Stage 2 – Focused Investigation
Toolkit Framework Stage 1 – Overview Investigation Maturation-Specific Maturation Data Reporting Age & Cause Stage 2 – Focused Investigation Environmental Attributes Health Services Maternal Attributes
Toolkit Framework Stage 1 – Overview Investigation Maturation-Specific Maturation Data Reporting Age & Cause Stage 2 – Focused Investigation Environmental Attributes Health Services Maternal Attributes
U A B SCHOOL OF PUBLIC HEALTH Maternal and Child Health Infant Mortality Assessment Manual Greg R. Alexander, RS, MPH, ScDSara Nabukera, M.D., MPHDeren Bader, MPHMartha Slay-Wingate, MPH University of Alabama at BirminghamSchool of Public HealthDepartment of Maternal and Child Health Introduction Purposes and Objectives Data Sources Questions for Assessment Statistical Analysis and Interpretation SAS Program References Appendix Home Website: http://www.soph.uab.edu/mch-imrm/index.htm
Toolkit Framework Stage 1 – Overview Investigation Maturation-Specific Maturation Data Reporting Age & Cause Stage 2 – Focused Investigation Environmental Attributes Health Services Maternal Attributes
State Infant Mortality Toolkit Stage 1 Hypotheses:Assessment of Changes in Maturity at Birth and Maturity-Specific Mortality The Maturity and Maturity-Specific Mortality Subgroup
Data In order to explore proposed birth maturity-related hypotheses that might explain infant mortality trends and develop examples for the SIMC Toolkit, we selected the following NCHS datasets: • U.S. Live Birth Cohort Linked files for 1985-1988 and 1995-2000; • U.S. Fetal Death files: 1985-1989 and 1995-2000.
Data Selection For this presentation we used the following case selection criteria: • Live births (1985-1988 and 1995-2000) to U.S. resident mothers; • Fetal deaths were excluded.
Maturity Hypothesis for Trends in Infant Mortality Formal Hypothesis: There is no association between the currently observed trends in infant mortality and any changes in the maturity at birth of infants as measured by birth weight, gestational age and fetal growth, e.g., small for gestational age.
Maturity Hypothesis for Trends in Infant Mortality Rationale: • One of the strongest predictors of infant death is the maturity of an infant at birth with infants at the extremes of maturity being at highest risk. • As infant mortality trends may be driven by changes in the proportion of these high risk infants, the examination trends in birth weight & gestational age distributions is indicated.
Maturity Hypothesis for Trends in Infant Mortality Possible Pathways: • Changes in proportion of high risk birth weight or gestational age infants, e.g., increase in very preterm or very low birth weight rates; • Changes in proportion of small-for-gestational age infants.
Changes in Birth Weight Categories by State 1985-1888 & 1995-2000
Birth Weight DistributionComments • Slight decrement in BW distribution between 1985-88 and 1995-2000 with increases in <500g, VLBW, and LBW rates, although macrosomic (4000+g) birth rates have decreased. • Similar trends evident in each target State. • Evidence suggests there has been an increase in rate of births with birth weights at the lower extreme of the BW distribution.
Birth Weight for Gestational Age Categories * Based on 1991 US reference curve
Birth Weight for Gestational Age Categories * Based on 1991 US reference curve
Birth Weight for Gestational Age Category (SGA) by State 1985-88, 1998-2000
Fetal Growth PatternsComments • Change in gestational age reporting between time periods made have altered shape of fetal growth patterns (note decline in both SGA and LGA). • SGA rates have declined, driven by decrease for term SGA infants. • Preterm SGA rates have increased.
Overall Changes in Maturity at DeliveryPreliminary Summary • During the last period, preterm, VLBW and LBW rates rose while infant mortality rate continued to decline. • While there is some evidence of a decrement in maturity at birth that could negatively influence infant mortality rates, improvement in infant mortality for the U.S. generally continued, suggesting that factors other than maturity at birth had a greater impact on infant mortality trends.
Suggested References • Alexander GR, Allen MC. Conceptualization, measurement, and use of gestational age. I. Clinical and public health practice. J Perinatol 1996; 16(1): 53-59. • Alexander GR, Slay M. Prematurity at birth: Trends, racial disparities, and epidemiology. Mental Retard Develop Disabilities Res Reviews 2002; 8: 215-220 • Blondel B, Kogan, MD, et al. The impact of the increasing number of multiple births on the rates of preterm birth and low birth weight: An international study. Am J Public Health 2002; 92:1323-1330. • Demissie K, Rhoads GG, et al. Trends in preterm birth and neonatal mortality among blacks and whites in the United States from 1989 to 1996. Am J Epid 2001; 154:307-315. • Kramer MS. Intrauterine growth and gestational duration determinants. Pediatrics 1987; 80: 502-11. • McCormick MC. Significance of low birth weight for infant mortality and morbidity. Birth Defects Orig Artic Ser 1988;24:3-10. • Oken E, Kleinman KP, et al. A nearly continuous measure of birth weight for gestational age using a United States national reference. BMC Pediatr 2003; 3:6. • Wilcox LS, Marks JS, eds. From Data to Action. Atlanta: Centers for Disease Control, 1994, pp 163-178.
Toolkit Framework Stage 1 – Overview Investigation Maturation-Specific Maturation Data Reporting Age & Cause Stage 2 – Focused Investigation Environmental Attributes Health Services Maternal Attributes
Maturity Specific Mortality Hypothesis for Trends in Infant Mortality Formal Hypothesis: • There is no association between the currently observed trends in infant mortality and any changes in mortality risk for specific maturity at birth categories, as measured by birth weight, gestational age and fetal growth, e.g., small for gestational age
Maturity Hypothesis for Trends in Infant Mortality Rationale: • Overall infant mortality trends may be driven by changes in the risk of mortality for specific maturity at birth groups, e.g., increases in the survival of VLBW infants may have a marked effect on overall infant mortality rates. • Therefore, trends in birth weight/gestational age specific infant mortality rates should be examined.
Maturity Specific Mortality Hypothesis for Trends in Infant Mortality Possible Pathways: • Changes in birth weight or gestational age-specific survival, e.g., no temporal improvement in survival for <1000 gram or <24 week infants; • Changes in survival of small-for-gestational age infants.
Summary • Both birth weight and gestational age specific mortality have improved nationwide, although such recent trends are not evident in every State, e.g., Hawaii. • These data suggest that the investigation of maturity-specific mortality is a viable hypothesis to explore for better understanding trends in infant mortality.
Suggested References • Alexander, GR, Kogan M, et al. U.S. birth weight-gestational age-specific neonatal mortality: 1995-7 rates for Whites, Hispanics and African-Americans. Pediatrics 2003; 111(1): e61-66. • Alexander GR, Tompkins ME, at el. Trends and racial differences in birth weight and related survival. MCHJ 1999; 3(1): 71-79. • Allen MC, Alexander GR, et al. Racial differences in temporal changes in newborn viability and survival by gestational age. Paediatr Perinat Epid 2000; 14(2): 152-158. • Kleinman JC, Kovar MG, et al. A comparison of 1960 and 1973-4 early neonatal mortality in selected states. Am J Epid 1978; 108: 454-469. • Lee KS, Paneth N, et al. Neonatal mortality: an analysis of the recent improvement in the United States. Am J Public Health 1980; 70:15-21. • Lee KS, Paneth N, et al. The very low-birth-weight rate: Principal predictor of neonatal mortality in industrialized populations. J Pediatr 1980; 97:759-64. • Lee KS, Khoshnood B, et al. Which birth weight groups contributed most to the overall reduction in the neonatal mortality rate in the United States from 1960 to 1986? Paediatr Perinat Epid 1995; 9:420-30. • Sappenfield WM, Buehler JW, et al. Differences in neonatal and postneonatal mortality by race, birth weight, and gestational age. Public Health Rep. 1987; 102(2): 182-192.
Toolkit Framework Stage 1 – Overview Investigation Maturation-Specific Maturation Data Reporting Age & Cause Stage 2 – Focused Investigation Environmental Attributes Health Services Maternal Attributes
State Infant Mortality Toolkit Stage 1:State Assessment of Timing & Cause of Death Thought:Different biologic causes may be impacting mortality
Study question To what degree could changes in the cause and timing of death explain: • Currently observed trends in fetal infant mortality rate? • Disparities in infant mortality? • Differences between states?
Possible pathways to be explored Changes in: • specific cause(s) of death • after accounting for possible changes in classification and certification preference • timing of death (age at death) • cause and/or timing of death within specific categories of birthweight, gestational age, race/ethnicity, etc.
Timing definitions for infant mortality Early fetal death: A fetal death between 20 and 27 weeks of gestation. Late fetal death: A fetal death after 28 weeks of gestation or more. Neonatal death: A death of a liveborn under 28 days of age. Early neonatal death: A death of a liveborn under 7 days of age. Late neonatal death: A death of a live born occurring between 7 and 27 days of age. Postneonatal death: A death occurring between 28 days and 11 months of age. Infant death: A death of a live born under 1 year of age.