Predictors of Low Birth Weight

And Geographic Access to Prenatal Care in Kansas,

1999

National Association for Public Health Statistics and Information Systems

Annual Meeting

June 7, 2006San Diego, CA

V. James Guillory, DO, MPH, FACPMGlynda Sharp, MHAGreg Crawford, BS

Practical Applications of Research on MCH at State

Level

Identifies specific areas and sources of concern where birth outcomes and maternal health can be improved

Provides important information so that resources can best be allocated to achieve the greatest improvement

Informs policymakers

Drives policy formation.

Traditional Predictors of Infant Mortality in the United States

Low birth weight (<2500 grams)*Preterm births (<37 weeks gestation)Prenatal care Early vs late initiation Adequacy *ACCESS to Prenatal care

Maternal factors health/morbidities (anemia, DM, HTN) behavioral (tobacco, ETOH, drugs, nutrition) demographic (race, teen birth rate,

education, marital status)

* The US ranks last of 13 developed nations in LBW

What We Know: Barriers to

Adequate Prenatal Care

Mothers in rural areas: Lack available local prenatal and

obstetrical care Less access to health insurance

less prenatal care visits start prenatal care later

Increased morbidity Greater distance and travel time to

providers Transportation problems Child-care difficulties for larger families

Importance of LBW

The rates of low birth weight are relatively unchangedover the past 35 years

LBW is a major predictor of infant morbidity and mortality

National Objectives Related to

Infant Health

Healthy People 2010 Reduce infant morbidity and mortality Decrease disparities in health

Comparison of Kansas Birth Outcomes to the United States and HP2010 Objectives, 1999

% Kansas % U.S. % HP 2010 TargetLow birth weight (<2500 grams) 6.99 7.6 5

Very low birth weight (<1500 grams) 1.24 1.5 0.9Total Preterm (<37 weeks)** 8.38 11.8 7.6

Live births 32-36 weeks 7.05 * 6.4Live births <32 weeks 1.33 1.96 1.1

* n = 38,194 (> 350 grams and > 20 weeks gestation)**Rate has risen steadily during the 1990's by about 11 percent

6.99

1.24

8.38

7.05

1.33

11.8

0

1.96

5

0.9

6.4

1.1

1.5

7.6 7.6

0

2

4

6

8

10

12

14

Low birth weight (<2500 g)

Very low birth weight (<1500g)

Preterm (<37 weeks)**

Live births 32-36 weeks

Live births <32 weeks

% Kansas % U.S. % HP 2010 Target

How Kansas Compares to the Nation: LBW

2002Kansas:

46 out of 51 (51 is Best)

Best: Alaska, 5.8%;

Worst:D.C., 11.6%Mississippi, 11.2%

Research ObjectivesAssess the quality of birth certificate data for use in multivariate statistical analysisAssess relationship between factors and LBW Maternal characteristics Prenatal care Insurance status Geographic location

Determine the predictors of low birth weight using regression analysis

Methods

Kansas Birth Certificate data linked to Medicaid Claims data, 1999Data file prepared by the Office of Vital Statistics, Kansas Department of Health and EnvironmentObtained IRB approval

Inclusion criteria Single live births Birthweight > 350 grams Gestation > 20 weeks

Exclusion Criteria Missing data for dependent or independent variables

of concern

Methods continued . . .

Methods (continued)

Primary outcomes Proportion of infants with low birth weight

Predictors of importance Geographic distribution Insurance status Other maternal characteristics

Geographic Distribution based on

2000 Census Bureau County

Designations Based on commuting patterns and their resulting economic resource flow3 Designations Metropolitan Micropolitan Non-metropolitan

Ratcliff MR. Creating Metropolitan and Micropolitan Statistical Areas.Office of Management and Budget. 1998. Alternative Approaches

to Defining Metropolitan and Non-metropolitan Areas. Federal Register, 63:244:70526-70561

Statistical MethodologyUnivariate analysis Chi square for tests of significance of

categorical variables Student’s t-test for analysis of continuous

variables Statistical significance at alpha < 0.05

Multiple regression analysis Logistic regression

Stepwise Only those variables with a p-value < 0.0001

were entered into the model

RESULTS

Kansas Births, 1999*38,748 births Number % Single Births 37,605 97.1 Twin Births 1,090 2.8 Triplet Births 53 0.1

Race White 34,483 89.2 Black/African American 2,841 7.4 Native American 365 0.9 Asian/HI/PI/Other 972 2.5

Gender Male 20,096 51.9 Female 18,652

48.1*All births

Association Between Maternal Demographic Characteristics and Low Birth Weight: Single Births (n=37081)

Infants with Low Birth Weight (< 2500 grams)

Maternal Race n % White 1667 5.04*African American 296 10.81Native American 16 4.57Asian/HI/PI/Other 56 6.03

Maternal Marital StatusMarried 1207 4.57*Not Married 828 7.79

Maternal Education<HS Grad 538 7.75*HS Grad 701 6.34Any College 796 4.17

Maternal Age<20 years old 366 7.65*20+ years old 1669 5.17

*p<0.0001

Association Between Prenatal Care, Medicaid and Low Birth Weight: Single Births

Infants with Low Birth Weight (< 2500 grams)

Trimester PN Care Began n % 1st Trimester 1673 5.26*

None or Later 362 6.86

Maternal Medicaid StatusNo Medicaid 1243 4.59*Moms with Medicaid 792 7.92

*p<0.0001

% Low Birth Weight (<2500 grams)

3.75

9.85

4.86

14.0413.04

5.435.625.46

0

2

4

6

8

10

12

14

16

YES NO YES NO YES NO YES NO

Under weight mother

Chi square = 15.2

p = <0.0001

Obesity >20%

Chi square = 16.9

p = <0.0001

Smoker

Chi square = 196.6

p = <0.0001

Alcohol Use

Chi square = 33.4

p = <0.0001

Association Between Maternal Behavior and LBW

% Low Birth Weight < 2500 grams

Uterine Bleeding Yes 11.72Uterine Bleeding No 5.43Hydramnios/Oligo Hydramnios Yes 18.9Hydramnios/Oligo Hydramnios No 5.36Eclampsia Yes 50Eclampsia No 5.47Pre-clampsia Yes 17.46Pre-clampsia No 5.05

Association between Maternal Medical Factors Associated with Pregnancy and Infant Low Birth Weight

% Low Birth Weight

(< 2500 grams)

11.72

5.43 5.36 5.47 5.05

17.4618.9

50

0

10

20

30

40

50

60

Yes No Yes No Yes No Yes NoUterine Bleeding

Chi2 = 27.723p = <.0001

Hydramnios / Oligo HydramniosChi2 = 120.3296

p = <.0001

EclampsiaChi2 = 61.1432

p = <.0001

Pre-clampsiaChi2 = 379.1178

p = <.0001

% Low Birth Weight <

2500 gramsOther STD Yes 8.07Other STD No 5.44

Hemoglobinopathy Yes 28.57Hemoglobinopathy No 5.48Cardiac Disease Yes 12.1Cardiac Disease No 5.47Chronic Hypertension Yes 17.32Chronic Hypertension No 5.41Lung Disease Yes 8.26Lung Disease No 5.46

Association between Maternal Medical Factors Not Associated with Pregnancy and Infant Low Birthweight

% Low Birth Weight

(< 2500 grams)

8.07

5.44

28.57

5.48

12.1

5.47

17.32

5.41

8.266.46

0

5

10

15

20

25

30

Yes No Yes No Yes No Yes No Yes NoOther STD

Chi2 = 8.7675p = 0.0031

HemoglobinopathyChi2 = 7.1922

p = 0.0073

Cardiac DiseaseChi2 = 10.4759

p = 0.0012

Chronic HypertensionChi2 = 569.0593

p = <.0001

Lung DiseaseChi2 = 5.2569

p = 0.0219

n=37,081

RACE n %

White (n=33064) 8173 24.72

African American (n=2739) 1521 55.53

Native American (n=350) 150 42.86

Asian/HI/PI/Other (n=928) 154 16.59

AGE Less than 20 years old (n=4786) 2744 57.33

20-34 years old (n=28178) 6896 24.47

35 or older years old (n=4117) 358 8.7

MARITAL STATUS Married (n=26443) 3797 14.36

Unmarried (n=10638) 6201 58.29

EDUCATION Less than HS Grad (n=6939) 4005 57.72

HS Grad (n=11057) 3995 36.13

Any College n=19085) 1998 10.47

Mom's With Medicaid

Characteristics of Kansas Mothers with Single Births

Mothers on Medicaid

% % p-value

LBW (<2500 grams) 7.92 4.59 <.0001

VLBW (<1500 grams) 1.39 0.74 <.0001

Preterm (<37 weeks) 8.55 6.33 <.0001

Very preterm (<32 weeks) 1.53 0.79 <.0001

Infant birth outcomes: comparison between mothers on Medicaid and not on Medicaid

Mothers not on Medicaidn=27083n=9998

Medicaid Non-Medicaid p-value % %Hepatitis, B/HBsAg 0.14 0.06 0.02

Genital Herpes 1.21 0.9 0.01

AIDS or HIV 0.03 0.01 0.1

Other STD 4.13 0.95 <.0001

Anemia (HCT <30) 2.51 1.33 <.0001

Hemoglobinopathy 0.04 0.01 0.07

Cardiac Disease 0.35 0.33 0.75

Diabetes 2.32 1.92 0.02

Hypertension, Chronic 0.64 0.7 0.52

Lung Disease 1.34 0.8 <.0001

Renal Disease 0.39 0.26 0.04

Association Between Medicaid and Conditions Not AssociatedWith Pregnancy

Medicaid Non-Medicaid % % p-value

Underwieght <10% 0.65 0.27<.0001

Obesity >20% 9.56 6.41<.0001

Smoker 25.54 7.85<.0001

Alcohol Use 1.13 0.45 <.0001

Behavioral Factors and Medicaid

Maternal Comorbidity and Comorbidity Associated with Pregnancy: Comparison Between Medicaid and Non-Medicaid

Medicaid Non-Medicaid

p-value

Any Comorbidity 56.49 40.76 <.0001

Uterine Bleeding 1.27 0.89<.0001

Incompetent Cervix 0.02 0.01 0.51

Isoimmunization 0.05 0.08 0.32

Hydramnios/Oligohydramnios 1.13 0.85 0.01

Eclampsia 0.06 0.04 0.34

Pre-Eclampsia 3.95 3.43 0.02

1999 Kansas BirthsBy Geographic Location

Metropolitan 23,460 63.3%

Micropolitan 8,735 23.6%

Non-metropolitan 4,885 13.2%

Low Birth Weight and Preterm Births in Kansas, 1999 Based on Geographic Distribution of Mother's County of Residence

n % n % n % p valuePreterm (<37 weeks) 1630 6.95 609 6.97 331 6.78 0.8980Term (37+ wks) 21831 93.05 8126 93.03 4554 93.22

LBW (<2500g) 1251 5.33 516 5.91 268 5.49 0.1315Normal (2500+g) 22210 94.67 8219 94.09 4617 94.51

Gestational Age

Metropolitan Micropolitan Non-Metropolitan

Birth Weight

Multiple Regression Analysis

Covariates were assessed to determine the independent contribution to LBW deliveries in Kansas while adjusting for all known variables that were very highly statistically associated (p< 0.001) with LBW (adjusted p-value because of multiplicity)

Adjusted Odds Ratio Estimates—LBW*  PointPredictor Estimate 95% CI p-valuePRETERM 41.756 37.386 46.638 <.0001NONWHITE 1.888 1.585 2.248 <.0001EDUCATION 0.868 0.757 0.996 0.0431PRIORBABY 1.238 1.097 1.399 0.0006UNMARRIED 1.243 1.089 1.419 0.0012UT. BLEEDING 1.802 1.196 2.714 0.0049HYDRAMNIOS 2.790 1.906 4.083 <.0001ECLAMPSIA 11.868 2.976 47.338 0.0005PRE-ECLAMPSIA 2.223 1.812 2.726 <.0001PREV. SGA/PT 2.143 1.640 2.799 <.0001CHRONIC HTN 2.561 1.628 4.029 <.0001OBESITY >20% 0.505 0.395 0.645 <.0001SMOKING 2.178 1.886 2.514 <.0001MEDICAID 1.205 1.056 1.375 0.0056

*Prenatal care drops out of the model

Conclusions

Rate of preterm and low birth weight infants in Kansas and disparities in these outcomes was similar to the nationWomen who did not have private insurance were less healthy and had worse birth outcomesWomen with Medicaid had a 20% increase in the likelihood of having a LBW infant when adjusting for other factors.

Conclusions Geographic Location Does Matter Women in micropolitan counties

Started prenatal care later based on average month of starting care

Had fewer prenatal visitsWere less likely to have private insuranceHad multiple indicators that increase

potential for worse birth outcomes less access to health care Poorer health

ConclusionsInsurance matters Late or no prenatal care greatest for

women without private insurance Birth outcomes worse for infants born to

mothers on MedicaidNeed to separate public insurance from no insurance

Results suggest that birth outcomes may be improved through increased focus on maternal health rather than prenatal care

Conclusions (continued )

“Poor access indicators most often suggest the need to make health care more affordable.” (Pathman DE, Ricketts III TC, Konrad Thomas. How Adults’ Access to Outpatient Physician Services Relates to the Local Supply of Primary Care Physicians in the Rural Southeast. Health Services Research. 2006;41:79-102)

Thanks To:

The Kansas Department of Health and Environment for funding a portion of this study and for providing data.The Kansas City University of Medicine and Biosciences for their generous support.Sue Min Lai, PhD, KUMCJohn Keighley, PhD, KUMCPradeep Chandra, MSIV, KCUMB