250 likes | 348 Views
Explaining the 2001-02 Infant Mortality Increase. Marian MacDorman, Joyce Martin, T.J.Mathews, Donna Hoyert, and Stephanie Ventura. Division of Vital Statistics National Center for Health Statistics Centers for Disease Control and Prevention. Infant Mortality Rate: United States, 1990-2002.
E N D
Explaining the 2001-02 Infant Mortality Increase Marian MacDorman, Joyce Martin, T.J.Mathews, Donna Hoyert, and Stephanie Ventura Division of Vital Statistics National Center for Health Statistics Centers for Disease Control and Prevention
Infant Mortality Rate: United States, 1990-2002 +3% SOURCE: National Vital Statistics System, NCHS, CDC.
Infant Deaths and Infant, Neonatal, and Postneonatal Mortality Rates: US, 2001-02
Infant Mortality Rates by Maternal Race and Ethnicity: United States, 2001 and 2002 2001 2002 SOURCE: National Vital Statistics System, NCHS, CDC
Infant Mortality Rates by Leading Causes: United States, 2001-02 [Rates per 100,000 live births] NOTE: Bold, underlined numbers indicate a statistically significant increase from the previous year. SOURCE: National Vital Statistics System, NCHS, CDC.
Infant Mortality Rates by Birthweight: United States, 2002 grams
Percent of Births and Infant Deaths by Birthweight, United States, 2002 SOURCE: National Vital Statistics System, NCHS, CDC
Components of Infant Mortality • The distribution of births by birthweight. • Birthweight-specific infant mortality rates (the mortality rate for infants at a given weight)
Number of Live Births at <750 grams, United States, 2001 and 2002 +3% +2% +5% Birthweight in grams SOURCE: National Vital Statistics System, NCHS, CDC
Infant Mortality Rates by Birthweight, United States, 2001 and 2002 Birthweight in grams SOURCE: National Vital Statistics System, NCHS, CDC
Direct Standardization Used to measure the proportion of the overall 2001-2002 infant mortality increase due to a change in: - The distribution of births by birthweight (98%) - Birthweight-specific infant mortality rates (2%)
Results by Period of Gestation • Increase in the number and percent of extremely preterm births (<28 weeks) • Significant increase in infant mortality rates for preterm (<37 weeks) and very preterm (<32 weeks) • Direct Standardization indicated that: • 61% of the increase was due to a change in the distribution of births by gestational age. • 39% due to a change in gestational age-specific infant mortality rates.
Contribution of Multiple Births to 2001-02 Infant Mortality Increase • Number of multiple births increased by: - 3% overall - 4% for <750 gram births • Changes for multiple births accounted for ¼ of the overall infant mortality increase • ¾ was due to changes for single births
Possible Factors that Might Explain the Increase in <750 Gram Births • Changes in reporting of births and/or fetal deaths. • Changes in the risk profile of births. • Changes in medical management of pregnancy.
Percent of Live Births and Fetal Deaths 20+ Weeks, by Birthweight: US, 2001-02 Live Births Fetal deaths 20+ weeks 0.432 48.6 0.419 47.8 SOURCE: National Vital Statistics System, NCHS, CDC
Percent of Fetal Deaths 20+ Weeks that Occur at 20-27 Weeks: States Reporting All Periods of Gestation and All Other States, Selected Years 17% gap 14% gap 18% gap 22% gap SOURCE: National Vital Statistics System, NCHS, CDC
The Potential Influence of Changes in the Risk Profile of Births
The Potential Influence of Changes in the Risk Profile of Births Increases in <750 gram births were: - concentrated mostly among 20-34 year old mothers - occurred for non-Hispanic white, non- Hispanic black, and Hispanic mothers
The Potential Influence of Changes in Medical Management of Pregnancy
Distribution of Births by Gestational Age: United States, 1990 and 2002 SOURCE: National Vital Statistics System, NCHS, CDC
Percent of Births with Induction of Labor by Gestational Age: U.S., 1990-2002
Percent of Births Delivered by Cesarean by Gestational Age: United States, 1990-2002
Conclusions 2001-2002 infant mortality increase: • Due almost entirely to an increase in <750 gram births • ¾ of the increase among singletons • increase mostly for women aged 20-34
Conclusions (cont.) • 2003 preliminary infant mortality rate is 6.9 • Not significantly different from 2002 rate of 7.0 • Preventing very preterm and very low birthweight deliveries is key to further lowering the US infant mortality rate.