Differential Reduction in Near-Term Births for White Vs. Black Births in Ohio, 2007-2010

BACKGROUND:   Preterm birth is associated with more than 75% of perinatal mortality and half of perinatal and long-term morbidity. Non-Hispanic Black (NHB) women are 60% more likely to have a preterm birth compared to non-Hispanic White (NHW) women and the cause of this disparity remains largely inexplicable. To improve birth outcomes by reducing unnecessary births before 39 weeks gestation, the Ohio Perinatal Quality Collaborative (OPQC) initiated a quality improvement initiative with 20 hospitals in 2008.  Statewide, a decrease in births at 36-38 weeks gestational (near-term) was observed from 2007-2010; however NHB experienced a smaller improvement than NHW. The purpose of this project was to determine why NHB experienced a smaller decrease in near-term births than NHW. 

METHODS:   Five explanations for the disparity were hypothesized and tested using vital statistics records for births in Ohio to NHW (n=418, 246) and NHB (n=93,709) women during 2007-10. Time trends were assessed with logistic regression and racial difference in trend was assessed by an interaction between year and race in the model. Cross-sectional differences were tested by Chi Square. 

RESULTS:   From 2007-2010, significant (p<0.05) decreases in near-term births were experienced for both NHW and NHB women overall (15% vs. 8%, respectively) and within OPQC hospitals (17% vs. 7.5%) (p-value for racial difference <0.0001).  Of NHB births, 70% occurred in OPQC hospitals vs. 41% of NHW births (p<0.0001). NHB women were more likely deliver <36 weeks vs. NHW (12.2% vs. 7.0%; p<0.0001) and at 36-38 weeks, the prevalence of medically indicated inductions were 3.9 vs. 3.7 (p <0.0007) and birth following spontaneous labor were 25.8% vs. 22.8% (p<0.0001). 

CONCLUSIONS: The observed disparity in the reduction in near-term birth was likely attributable to the OPQC initiative being less likely to impact NHB births. While NHB women were more likely to deliver in an OPQC hospital than NHW, near-term births among NHB decreased less than among NHW both overall and within OPQC hospitals. Birth prior to 36 weeks, when the initiative was targeted, was more common among NHB. After reaching 36-38 weeks, NHB women were more likely to have spontaneous labor or a medical indication for induction, both outside the purview of the initiative. While the initiative reduced near-term births for both NHB and NHW women, disparities increased. To eliminate disparities in preterm birth, approaches must target the common reasons for birth <39 weeks among NHB women: early and spontaneous preterm births and medical indications for induction before 39 weeks gestation.