The impact of prenatal care adequacy on birth outcomes among documented and undocumented Hispanics i

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The impact of prenatal care adequacy on birth
outcomes among documented and undocumented
Hispanics in Texas

• Kathleen ORourke, PhD
• Andrea Thurman, MD,
• Chelsea Bowen, MPH
• Sarah McKinnon
• University of South Florida
• University of Texas at San Antonio
• University of Texas at Austin

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15 of the US is Hispanic 36 of Texas residents
are Hispanic
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254 Texas Counties
Dallas
El Paso
Harris
Bexar
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Research question 1

• Is the association of adequate prenatal care with
  low birth weight different for documented versus
  undocumented Hispanics?

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Research question 2

• Does the association of adequate prenatal care
  with low birth weight by documented versus
  undocumented Hispanics differ by county?

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Prenatal care overview

• Provision of antepartum medical care to women
• Ideally begun in the first trimester of
  pregnancy, increased frequency throughout the
  pregnancy
• Addresses medical, social, psychological,
  nutritional, and educational needs of pregnant
  women

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Measuring Prenatal Care

• Usually defined very crudely
• Some PNC vs. no PNC
• Month or trimester of 1st PNC visit
• Total of PNC visits
• A composite measure (Kotelchuck Index)
• Based upon a combination of timing and number of
  visits
• Approaches do not define components of PNC

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What is the effectiveness of PNC in preventing
poor pregnancy outcomes?

• We really dont know
• Why?
• Studies showing a positive overall impact have in
  general not removed the effect of self-selection
  bias or confounding
• Studies showing a negative overall impact have in
  general not been able to deal with error in
  measurement of PNC
• Some studies show effect for sub-populations but
  also suffer from methodological problems of bias

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Who does not receive adequate prenatal care?

• 4 distinct groups of non-PNC attenders
• Young, unmarried women
• Multiparous women with good prior pregnancy
  outcomes
• Women with poor obstetric history and massive
  social problem
• Undocumented immigrants with little or no access
  to care

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Adequate/adeq prenatal care by
race/ethnicity US, 2000-2002 Average
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Infant outcomes

• Low birth weight
• lt2500 grams
• Primary cause of neonatal morbidity and mortality
  in the US
• Preterm birth (not presented here)
• lt37 weeks gestation
• More challenging to measure
• These outcomes are correlated but not identical.

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Causes of low birth weight

• Premature birth
• About 67 percent of low-birthweight babies are
  premature
• Small-for-date babies
• Poor fetal growth

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Low birthweight
US, 2004
Low birthweight is less than 2500 grams (5 1/2
pounds). Source National Center for Health
Statistics, final natality data. Retrieved April
9, 2008, from www.marchofdimes.com/peristats.
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   Low birthweight by race Texas, 2002-2004
average
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Methology
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Data

• 2005 Birth certificate data for Texas
• Bexar, El Paso, Dallas, and Harris
• include San Antonio, El Paso, Dallas, and Houston
  
• Classification of Hispanics
• Documented
• Hispanic ethnicity and has a SSN
• Undocumented
• Hispanic ethnicity, no social security number
  (SSN), and birthplace of Mexico or South/Central
  America on the birth certificate.
• Prenatal care
• Kotelchuck Index
• Low birth weight
• lt2500 grams

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Statistical methods

• Chi-square for bivariate analyses
• Multivariate logistic regression analysis
• Assessed for interaction
• immigration status and the impact of adequacy of
  PNC on birth outcomes
• Birth county and PNC adequacy.

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Results
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Comparison of Demographic Characteristics for
Hispanics by Immigration Status
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Comparison of Obstetric Characteristics for
Hispanics by Immigration Status
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The association of ethnicity and adequacy of
prenatal care with low birth weight
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Impact of interaction of prenatal care and
immigrant status on low birth weight
Model includes immigration status, county, age
group, education, marital status, tobacco use in
the third trimester, gestational diabetes.
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Adjusted odds ratio for adequacy of prenatal care
documentation status with low birth weight by
county
Model includes immigration status, county age
group, education, marital status, Tobacco use in
the third trimester, gestational diabetes.
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Conclusions

• Undocumented Hispanics had the highest rates of
  inadequate PNC across all counties studied.
• However, undocumented Hispanics had fewer low
  birth weight infants than all other ethnicities,
  including non Hispanic Whites.
• This epidemiological paradox has been reported
  previously.

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Important differences between documented and
undocumented women

• Association of inadequate prenatal care with low
  birth weight is greater for documented than
  undocumented Hispanics.
• Conversely, we see less benefit of prenatal care
  for undocumented Hispanics.

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County differences in low birth weight

• Interesting County variations
• Variation in association of inadequate prenatal
  care and low birth weight among undocumented
  Hispanics
• Significant for Dallas and Harris
• Borderline for Bexar
• Non-significant for El Paso
• Less effect for undocumented Hispanics in more
  border counties

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Remaining questions

• Why does prenatal care show a differential
  association by documentation status?
• Nativity
• Selection bias
• Information bias (care in Mexico under-reported)
• Why are there county differences?
• Variation in services
• Variation in access

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Future studies

• Evaluate the effect of the country of birth
• Identify other associations
• Expand this study to more regions
• National Childrens Study

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Questions?
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The association of ethnicity and adequacy of
prenatal care with preterm delivery
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Impact of interaction of prenatal care and
immigrant status on preterm birth
Model includes immigration status, county, age
group, education, marital status, tobacco use in
the third trimester, gestational diabetes.
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Adjusted odds ratio for adequacy of prenatal care
documentation status with preterm delivery by
county
Model includes immigration status, county age
group, education, marital status, Tobacco use in
the third trimester, gestational diabetes.