Impact of Previous Preterm Birth and Interbirth Interval Length on Subsequent Adverse Birth Outcomes in African American Women Open Access

Sneed, Jessamyn Vania (2013)

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Preterm birth (PTB) complicates approximately 12% of all deliveries in the United States and, in addition to low birthweight (LBW), is classified as an adverse birth outcome due to its association with significantly higher rates of neurodevelopmental morbidity. The 2011 National Vital Statistics Report states that non-Hispanic black infants have the highest rates of preterm birth and low birthweight (16.75% and 13.33%, respectively) compared to Hispanic infants and non-Hispanic white infants in the United States. The exact cause of these increased rates of ABO in the African American community is unknown, but recent studies have implicated interbirth intervals and history of preterm birth among other variables. This study was conducted using data from the Pregnancy Risk Assessment Monitoring System, a surveillance project of the Centers for Disease Control and Prevention which collects nationwide data on maternal attitudes and experiences before, during, and after pregnancy. This cohort provided an unprecedented opportunity to study the multiplicative effect of interbirth interval (IBI) length and previous preterm birth on adverse birth outcomes. This study population consisted of 11,093 women. A forward elimination approach was used to develop logistic regression models which were used to estimate the odds of a study participant's current pregnancy being preterm or low birth weight. In addition to the two covariates of interest, thirteen predictors were included in each model: maternal BMI, race, income, marital status, age, education, history of hypertension and diabetes, recent miscarriage status, number of previous live births, smoking and drinking habits during pregnancy, and prenatal care seeking behavior. Mothers with IBIs of four years were shown to have the lowest statistically significant odds of having a subsequent PTB (aOR =0.67, p = 0.002) when compared to the referent group, mothers with IBIs of two years. Women with IBIs less than one year had significantly higher odds of subsequent LBW (aOR = 4.64, p=0.028) compared to the same reference group. African American women had statistically increased odds of having a subsequent LBW infant (aOR =1.96, p<0.0001) compared to White women. The results of this study, if confirmed, suggest that the ideal interbirth interval is four years.

Table of Contents

I. Introduction...1
II. Methods...8

Study Population...8
Data Description...9
Statistical Analysis...10

III. Results...12
IV. Discussion...18
V. Conclusion...22

VI. References...23

VII. Tables...27

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