Differing First Year Mortality Rates of Term Births to US-born and Foreign- born Mothers James W. Collins, Jr. 11/7/15

Transgenerational Factors Factors, conditions, and environments experienced by one generation that relate to the pregnancy outcome of the next generation

Differing Birth Weight in Illinois (David and Collins, NEJM, 1997)

Differing LBW Rates Among Low-risk Women in Illinois (David and Collins, NEJM, 1997)

Differing VLBW Rates Among Low-risk Women in Illinois (David and Collins, NEJM, 1997)

Maternal Race and Infant Birth Weight Among Low-Risk Women in Illinois (Pallotto et al, AJE, 2000)

Low Birth Rates by Maternal Age among Foreign-born Black Mothers (Deal et al, Ethn Dis, 2014)

VLBW RATES OF MEXICAN-AMERICANS BY MATERNAL GENERATIONAL RESIDENCE IN THE U.S. Collins and David, Ethn Dis, 2004)

Genetic Code vs. Zip Code? Two Leading Theories: “Genetic Code Theory”: –AA and MA women migrants to the US are intrinsically healthier and have better birth outcomes than those who do not migrate (Wingate, SSM, 2006; Ray et al, CMAJ, 2007). “Zip Code Theory”: –Lifelong residence in the US, or something closely related to it, is detrimental to the birth outcome of AA and MA women (David and Collins, AJPH, 2007; Collins and David, Clinics Perinat, 2009; Parker-Dominguez, SSM, 2010)

Testing the Genetic Theory Wingate et al, MCHJ 2009: –US-born Blacks who moved out of state had better birth outcomes compared to those who did not move, even after risk factors were controlled. –Data support the healthy migrant theory. –Limitation: No adjustment for neighborhood income.

Study Objective To determine the association between migration from Chicago to the suburbs and preterm birth (<37 wks, PTB) rates among African Americans and Whites.

Natural Experiment: White Flight from Chicago Chicago Suburban Cook Collar Counties map.gif

White Mothers N= 45, 135 African-American Mothers N=41, 221 White mothers were more likely to migrate Collins et al, MCHJ, 2013 P<0.0001, chi square test

PTB rates improved with migration for both races Collins et al, MCHJ, 2013 PTB rates/10 0 births p<0.05

White mothers who migrated had less risk factors. White Mothers: Distribution of Risk Factors ChicagoCookCollar Maternal Age <208%2% Education <12 yrs19%5% Unmarried25%8%7% Smoker24%18%16% Inadequate Prenatal Care14%6% Neighborhood Income in Lowest Quartile 21%<1%

AA mothers who migrated had less risk factors factors. African-American Mothers: Distribution of Risk Factors ChicagoCookCollar Maternal Age <2027%16%19% Education <12 yrs36%15%22% Unmarried83%55%58% Smoker20%15%18% Inadequate Prenatal Care33%21%32% Neighborhood Income in Lowest Quartile 74%16%4%

Migration benefits were explained by known risk factors Collins et al, MCHJ, 2013 Adjusted OR (95% CI) Chicago-Chicago Reference Chicago-Cook OR= 0.9 (0.8, 1.1) Chicago-Collar OR= 0.9 (0.8, 1.1) Adjusted OR (95% CI) Chicago-Chicago Reference Chicago-Cook OR= 0.9 (0.8, 1.2) Chicago-Collar OR= 1.0 (0.9, 1.3) WhitesAfrican-Americans

Implications Our findings do not support the healthy migrant theory as a valid explanation for the discrepancy in birth outcomes between foreign- and US-born AA and MA women.

Change in Mean Birth Weight Across a Generation (Collins et al, AJE, 2002) African/Carib- AA

Change in Mean Birth Weight Among infants of Married Women Across a Generation (Collins et al, AJE, 2002) African/Carib- AA

MLBW Rates Across a Generation (Collins et al, AJE, 2002)

MLBW Rates Among Infants of Married Women Across a Generation (Collins et al, AJE, 2002)

Study Objective To explore the birth weights of the direct female descendants of US-Born and Mexican-Born Mexican-American Women.

Change in Mean Birth Weight Across a Generation Mexican-born MA

Change in Mean Birth Weight Between Gen 2 and Gen 3 among the Female Descendants of Gen 1 Mexican-Born Women marriedunmarried< 20yrs Overall 20-35yrs -28 (-63, 7) -108 (-166, 50) 6 (-14, 26) -67 (-118, 16) -16 (-39, 10)

Term Infants

Study Objectives To determine whether maternal birth in the US is a risk factor for first year mortality among term (37-42 wks) births to non-Latino White, AA, and MA mothers. To ascertain the degree to which known individual level risk factors modify the relationship between maternal nativity and IMR among White, AA, and MA term births.

Methods National Center for Health Statistics linked live birth-infant death cohort files of term (37-42 wks) births to non-Latino White, AA, and MA mothers. Infant variables: birth weight, first year mortality. Maternal variables: nativity, age, education, parity, marital status, adequacy of prenatal care utilization (Kotelchuck Index). Stratified and multivariable binomial regression analyses were performed.

Term IMR by Maternal Nativity and Race/Ethnicity (Collins et al, MCHJ, 2013) n=3,684,569 n=118,246 # deaths/1,000 live births

Leading Cause-Specific Term IMR (per 1,000) by Maternal Race/Ethnicity and Nativity (Whites) (Collins et al, MCHJ, 2013) Leading Cause of Death White US-born White Foreign-born RR (CI 95%) Congenital Anomalies ( ) SIDS ( ) Injuries ( )

Leading Cause-Specific Term IMR (per 1,000) by Maternal Race/Ethnicity and Nativity (AA) (Collins et al, MCHJ, 2013) Leading Cause of Death AA US-born AA Foreign-born RR (CI 95%) Congenital Anomalies ( ) SIDS ( ) Injuries ( )

Leading Cause-specific Term IMR by Maternal Race/Ethnicity and Nativity (MA) Leading Cause of Death MA US-born MA Mexican-born RR (CI 95%) Congenital Anomalies (0.7—0.9) SIDS ( ) Injuries ( )

Distribution of Selected High-Risk Individual Level Risk Factors by Maternal Nativity (Whites) US-Born White N=3,684,569 Foreign-Born White N=226,621 LBW (<2500g)2.5%2.3% Maternal Age <20y7.5%2.5% Maternal Education <12y11.0%7.7% Parity 3+8.5%9.0% Unmarried23.9%10.6%

Term IMR by Maternal Age and Nativity (Whites) # deaths/1,000 live births Maternal Age (years)

Term IMR by Maternal Education and Nativity (Whites) # deaths/1,000 live births Maternal Education (years)

Term IMR by Marital Status and Nativity (Whites) Marital Status * Signfies statistical significance # deaths/1,000 live births

Distribution of Selected High-Risk Individual Level Risk Factors by Maternal Nativity (AA) US-Born AA N=782,452 Foreign-Born AA N=118,246 LBW (<2500g)5.7%3.6% Maternal Age <20y17.5%4.2% Maternal Education <12y24.3%14.8% Parity %13% Unmarried72.5%38.9%

Term IMR by Birth Weight and Nativity (AA) Marital Status * Signfies statistical significance # deaths/1,000 live births

Term IMR by Maternal Age and Nativity (AA) # deaths/1,000 live births Maternal Age (years)

Term IMR by Maternal Education and Nativity (African-Americans) # deaths/1,000 live births Maternal Education (years) * Signfies statistical significance

Term IMR by Marital Status and Nativity (AA) Marital Status * Signfies statistical significance # deaths/1,000 live births

Distribution of Selected High-Risk Individual Level Risk Factors by Maternal Nativity(MA) US-Born MA N=388,337 Foreign-Born MA N=710,837 LBW (<2500g)2.5%2.3% Maternal Age <20y12.5%6.5% Maternal Education <12y31.4%65.5% Parity %15.6% Unmarried48.2%41.2%

Term IMR by Maternal Age and Nativity (MA) # deaths/1,000 live births Maternal Age (years)

Term IMR by Maternal Education and Nativity (Mexican-Americans) Maternal Education (years) * Signfies statistical significance # deaths/1,000 live births

Term IMR by Marital Status and Nativity (MA) Marital Status * Signfies statistical significance # deaths/1,000 live births

Multivariable Binomial Regression Analyses (Collins et al, MCHJ, 2013) The adjusted (controlling for maternal age, education, parity, adequacy of prenatal care and region of birth) RR of infant mortality for non-LBW term births of US-born (compared to Foreign-born) White, AA, and MA mothers were 1.5 ( ), 1.7 ( ), and 1.6 ( ), respectively. The adjusted OR of SIDS among US-born (compared to Foreign-born) White, AA, and MA mothers were 3.1 ( ), 2.8 ( ), and 2.9 ( ), respectively.

Limitations Vital records do not include duration of US residence for foreign-born mothers. No information on neighborhood level factors. No information of adequacy of the utilization of pediatric care.

Conclusions Term births to US-born White mothers have a 1.7-fold greater IMR than their peers with foreign-born mothers independent of the known individual level risk factors. The disparity is not limited to a singular cause of death and is widest among deaths due to SIDS. A similar phenomenon occurs among African- Americans and Mexican-Americans.

Conclusions US-born mothers have approximately a 3- fold greater SIDS rate than their peers with foreign-born mothers. More detailed studies are needed to determine the extent to which term infant sleep positioning modifies the association of maternal nativity and SIDS.

Implications The fact that the same phenomenon occurs among the three leading racial/ethnic groups in the US pinpoints the problem to the presence of risk factors among US-born women (i.e. lifelong residence in the US) rather than to the presence of protective factors among foreign-born women (i.e. healthy immigrant hypothesis).

Implications Our findings do not support the healthy migrant theory as a valid explanation for the discrepancy in birth outcomes between foreign- and US-born African-American women.

Speculation Unmeasured household factors underlie the maternal nativity disparity in term infant outcome regardless of race or ethnicity. Possibilities include maternal nativity differences in daycare practices and/or the presence of extended family members residing in the home.

Term IMR by Maternal Nativity and Race/Ethnicity (Collins et al, MCHJ, 2013) n=3,684,569 n=118,246 # deaths/1,000 live births

Study Objective To determine the extent to which maternal demographic risk factors explain the racial disparity in IMR among term infants.

Leading Cause-Specific IMR (< 365d) by Race deaths/1,000 live-births

Cause Specific Neonatal Mortality Rate (NMR, <28d) by Race deaths/1,000 live-births

Cause Specific Post-neonatal Mortality Rates (PNMR, d) by Race deaths/1,000 live-births

Distribution of Selected Risk Factors %

Term IMR among Low-Risk* White and African-American Mothers deaths/1,000 live-births *married, college-educated mothers who received adequate prenatal care adequate prenatal care

Multivariable Binomial Regression Models  The raw and adjusted RR for infant death (365d) for AA (compared to Whites) were 1.7 ( ) and 1.1 ( ), respectively  The raw and adjusted RR for neonatal death (<28d) for AA (compared to Whites) were 1.3 ( ) and 1.0 ( ), respectively  The raw and adjusted RR for post-neonatal deaths (28-365d) for AA (compared to Whites) were 2.0 ( ) and 1.1 ( ), respectively