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Changing Risk Factors for Infant Mortality — Delaware, 1994–2001

Changing Risk Factors for Infant Mortality — Delaware, 1994–2001. Marci Drees, MD EPO, State Branch Delaware Health & Social Services. Infant Mortality Trends* (3-Year Moving Averages). 15. US. 14. 13. DE. 12. 11. Deaths per 1,000 live births. 9.2. 10. 9. 8. 6.9. 7. 6. 0.

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Changing Risk Factors for Infant Mortality — Delaware, 1994–2001

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  1. Changing Risk Factors for Infant Mortality —Delaware, 1994–2001 Marci Drees, MD EPO, State Branch Delaware Health & Social Services

  2. Infant Mortality Trends* (3-Year Moving Averages) 15 US 14 13 DE 12 11 Deaths per 1,000 live births 9.2 10 9 8 6.9 7 6 0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 Year *Unlinked data

  3. Study Objectives Investigate the following hypotheses: • Increase in plurality (multiple births) • Increase in low birthweight infants • Increase in birthweight-specific mortality

  4. Data Source • Linked birth-death certificate cohort data from 1994–2001 • All live births to Delaware residents • Completeness of data: • Delaware linkage 100.0% • National linkage 98.9%

  5. Comparative Time Periods • 1994 – 1996 • Lowest IMR of 7.1 • 220 infant deaths • 30,802 live births • 1999 – 2001 • Most recent IMR of 8.8 • 286 infant deaths • 32,459 live births

  6. Analyses • Adjusted infant mortality rates: • For plurality distribution • For birthweight distribution • Stratified analyses examined IMR trends: • Within plurality and birthweight subgroups • According to maternal characteristics

  7. Plurality & Birthweight Distributions

  8. Infant Mortality Rates 9.0 8.8 Unadjusted 8.0 Deaths per 1,000 live births 7.0 7.1 0.0 1994–1996 1995–1997 1996–1998 1997–1999 1998–2000 1999–2001 Years

  9. Infant Mortality Rates 9.0 8.8 8.6 Adjusted for plurality distribution Unadjusted 8.0 Deaths per 1,000 live births 7.0 7.1 0.0 1994–1996 1995–1997 1996–1998 1997–1999 1998–2000 1999–2001 Years

  10. Infant Mortality Rates 9.0 Adjusted for BW distribution 8.8 8.6 Adjusted for plurality distribution Unadjusted 8.2 8.0 Deaths per 1,000 live births 7.0 7.1 0.0 1994–1996 1995–1997 1996–1998 1997–1999 1998–2000 1999–2001 Years

  11. Birthweight-Specific Mortality 350 311.5 1994–1996 * 300 1999–2001 235.0 250 200 Deaths per 1,000 live births 150 100 50 16.1 14.5 2.1 2.4 0 Normal BW (>2,500g) MLBW (1,500–2,499g) VLBW (<1,500g) Birthweight

  12. Infant Mortality Rates 9.0 Adjusted for BW distribution 8.8 8.6 Adjusted for plurality distribution Unadjusted 8.2 8.0 Deaths per 1,000 live births 7.0 7.1 0.0 1994–1996 1995–1997 1996–1998 1997–1999 1998–2000 1999–2001 Years

  13. Infant Mortality Rates Adjusted for BW distribution & assumed constant VLBW IMR 9.0 Adjusted for BW distribution 8.8 8.6 Adjusted for plurality distribution Unadjusted 8.2 8.0 Deaths per 1,000 live births 7.0 6.9 7.1 0.0 1994–1996 1995–1997 1996–1998 1997–1999 1998–2000 1999–2001 Years

  14. IMR Trends Among VLBW Infants by Plurality 600 1994–1996 536 * 1999–2001 500 400 314 297 Deaths per 1,000 live births 300 * 261 200 160 95 100 0 Singletons Twins Triplets/+ Plurality Categories

  15. IMR Trends Among VLBW Infants by Gestational Age 600 528 500 * 1994–1996 407 1999–2001 400 300 Deaths per 1,000 live births 200 78 73 100 0 0 0 <28 weeks 28–36 weeks >36 weeks Gestational age

  16. IMR Trends Among VLBW Infants by Maternal Age 347 350 318 306 * 300 271 248 250 200 Deaths per 1,000 live births 152 1994–1996 150 1999–2001 100 50 0 <20 years 20–29 years >30 years Maternal Age

  17. IMR Trends Among VLBW Infants by Marital Status 350 322 313 303 * 300 250 200 Deaths per 1,000 live births 150 150 1994–1996 100 1999–2001 50 0 Single Married Marital Status

  18. IMR Trends Among VLBW Infants by Maternal Education 400 1994–1996 344 1999–2001 333 350 302 300 276 265 * 250 Deaths per 1,000 live births 200 144 150 100 50 0 < 12 yrs High school >1 yrs college Maternal education

  19. IMR Trends Among VLBW Infants by County/City of Residence 350 330 315 301 289 293 288 * 300 280 250 1994–1996 200 177 Deaths per 1,000 live births 1999–2001 150 100 50 0 Kent Co. Sussex Co. Wilmington Other New Castle Co. County/City of Residence

  20. IMR Trends Among VLBW Infants by Source of Payment 489 500 1994–1996 450 425 1999–2001 400 350 312 282 279 * 300 Deaths per 1,000 live births 250 181 200 150 100 50 0 Self-pay Medicaid Private Insurance Source of Payment

  21. IMR Trends Among VLBW Infants by 1st Trimester Prenatal Care 350 311 295 * 300 281 250 224 200 Deaths per 1,000 live births 150 1994–1996 100 1999–2001 50 0 No Yes Initiation of Prenatal Care in 1st Trimester

  22. Summary of Maternal Factors Suggest higher socioeconomic status • >30 years of age • Married • More educated • Suburban • Private insurance • Early prenatal care

  23. Etiology? • Delayed childbearing, infertility and infertility treatments • Changes in perinatal practices • Shift from fetal deaths to neonatal deaths • Classification • Fetal survival

  24. Assisted Reproductive Technology in Delaware Increasein ART-conceived infants to Delaware residents • 13% increasein ART procedures in DE from 1996–2000 • Increased ART in surrounding states (MD, NJ, PA) • Increased ART success rates

  25. 2000 Delaware Birth Cohort • 1% conceived via ART • 7.5% VLBW infants via ART • Of multiple births: • 55.6% expected from natural conception • 16.8% attributable to ART • 27.6% from other infertility treatments

  26. Other Infertility Concerns • Other infertility treatments • Ovarian hyperstimulation • Not well-monitored or studied • Infertility itself • Subfertility • Higher rates of low birthweight

  27. Detailed Birthweight Distribution 1.9 2.0 1994–1996 1.7 1.8 1999–2001 1.6 1.4 1.2 Percent 1.0 0.88 0.80 0.72 0.8 0.68 0.6 0.4 0.29 0.21 0.2 0.0 Total VLBW <500g 500–999g 1,000–1,499g Birthweight

  28. IMR Trends by Detailed Birthweight Category 1,000 904.3 900 * 800 757.6 1994–1996 1999–2001 700 600 500 Deaths per 1,000 live births 400.9 400 * 311.5 310.7 300 235.0 200 100 42.3 28.8 0 Total VLBW <500g 500–999g 1,000–1,499g Birthweight

  29. Age of Infant Deaths 70 61.9 1994–1996 60 * 1999–2001 51.9 50 40 35.0 Percent (%) 30 26.2 20 13.2 11.9 10 0 Early neonatal Late neonatal Postneonatal (0–6 days) (7–27 days) (28–364 days) Age at Death

  30. Fetal Mortality Rates • FMR = fetal deaths X 1,000 live births + fetal deaths • DE fetal death rate data unreliable • Christiana Hospital • Approximately 50% of DE births • Tertiary referral center • Only high-level neonatal care in state • Primary hospital serving New Castle County

  31. Christiana Infant & Fetal Mortality Rates 11.6 12 11.0 10.8 10.2 11 10 9.2 9 8.0 Deaths per 1,000 live births 8 8.0 7 7.3 7.1 6 6.5 5.7 5 5.2 0 1994–1996 1995–1997 1996–1998 1997–1999 1998–2000 1999–2001 Years Fetal mortality rate Infant mortality rate

  32. Limitations • Small numbers of infant deaths • Unable to directly link ART to infant mortality • Unable to assess infertility & non-ART treatments • Unable to evaluate quality or content of perinatal care

  33. Conclusions • Delaware’s increasing IMR primarily due to: • Increasing mortality among VLBW infants • Increasing frequency of LBW • Maternal profile suggested increased mortality among higher socioeconomic status

  34. Conclusions (2) • Likely multifactorial etiology • Infertility and/or its treatments • Changes in fetal classification or reporting • Improvement in fetal survival

  35. Future Directions • Collaboration between Delaware DPH, Perinatal Board and CDC Division of Reproductive Health • Further analysis of state vital statistics, other data sources • Independent research on illness severity • Consider adding method of conception to birth certificate

  36. Delaware Division of Public Health Paul Silverman, DrPH Leroy Hathcock, PhD Ted Jarrell, PhD Delaware Health Statistics Center Christiana Care Judy Walrath, PhD Gina Moore, RN CDC, Division of Reproductive Health Laura Schieve, PhD Cynthia Ferré, MS Meredith Reynolds, PhD William Sappenfield, MD, MPH EPO, State Branch David Callahan, MD Anindya De, PhD Acknowledgments

  37. IMR Trends Among VLBW Infants by Race/Ethnicity 400 1994–1996 1999–2001 350 330 320 291 300 261 * 259 250 205 Deaths per 1,000 live births 200 150 100 50 0 Non-Hispanic White Non-Hispanic Black Hispanic Racial/Ethnic Group

  38. IMR Trends Among VLBW Infants by Cause of Death 90 83.5 81.9 80 1994–1996 70 1998–2000 60 50 Deaths per 1,000 live births 40 28.4 30 25.1 * 17.5 20 15.5 15.1 7.8 10 1.9 1.7 0 Short gestation Congenital SIDS Maternal Respiratory / LBW malformations complications distress Cause of death

  39. Proportion of Excess VLBW Deaths by Plurality, 1999–2001 Singletons Triplets/+ 13% 22% n = 33 Twins 65%

  40. Percent Change in IMR Among VLBW Infants from 1994–1996 to 1999–2001 by Detailed BW Category 80 70 60 Percent Change in IMR 50 47 40 29 30 19 20 10 0 <500g 500–999g 1,000–1,499g Birthweight

  41. IMR Trends Among VLBW Infants by Mother’s Age 400 336 350 1994–1996 321 316 299 1998–2000 300 274 269 250 227 209 Deaths per 1,000 live births * 200 175 150 109 100 50 0 <20 20–24 25–29 30–34 >35 Mother's age (years)

  42. Birthweight-Specific Mortality 1,000 904.8 900 757.6 800 1994–1996 700 1998–2000 600 500 Deaths per 1,000 live births 385.7 400 310.7 300 200 100 48.1 28.8 26.4 14.6 16.6 9.8 2.4 2.5 0 <500g 500–999g 1,000– 1,500– 2,000– >2,500g 1,999g 2,499g 1,499g Birthweight

  43. Age of VLBW Infant Deaths 100 90 76.1 80 71.9 70 1994–1996 60 1998–2000 Percent (%) 50 40 30 15.7 20 15.3 12.4 8.5 10 0 Early neonatal Late neonatal Postneonatal Age at death

  44. IMR Trends Among Women >30 Years by Race/Ethnicity 20 17.7 18 * 16 14 12 Deaths per 1,000 live births 10 8.4 8 6.2 1994–1996 6 * 1998–2000 3.3 4 2 0 Non-Hispanic White Non-Hispanic Black Race/Ethnicity

  45. Detailed Birthweight Distribution of VLBW Infants 100 1994–1996 1999–2001 80 Percent (%) 60 46.6 47.3 VLBW 40.1 38.0 40 infants 15.4 20 12.6 0 <500g 500–999g 1,000–1,499g Birthweight

  46. IMR Trends Among VLBW Infants by Detailed BW Category 1,000 904.3 900 * 800 757.6 1994–1996 700 1999–2001 600 Deaths per 1,000 live births 500 400.9 400 * 310.7 300 200 100 42.3 28.8 0 <500g 500–999g 1,000–1,499g Birthweight

  47. City of Wilmington New Castle County Dover Kent County Sussex County

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