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Updated: Jan 23, 2026

A Novel Method for Involving Women of Color at High Risk for Preterm Birth in Research Priority Setting
Published on: January 12, 2018
Short interpregnancy interval as a risk factor for preterm birth in non-Hispanic Black and White women in California
Julia A Lonhart1, Jonathan A Mayo1, Amy M Padula2
1March of Dimes Prematurity Research Center at Stanford University School of Medicine, Stanford, CA, USA.
Objective:
Short interpregnancy interval (IPI) is associated with adverse pregnancy outcomes, including preterm birth (PTB < 37 weeks GA). We investigated whether short IPI (< 6 months) contributes to the higher PTB frequency among non-Hispanic Blacks (NHB).
Study Design:
Using a linked birth cohort > 1.5 million California live births, we examined frequencies of short IPI between racial/ethnic groups and estimated risks by multivariable logistic regression for spontaneous PTB. We expanded the study to births 1991-2012 and utilized a "within-mother" approach to permit methodologic inquiry about residual confounding.
Results:
NHB women had higher frequency (7.6%) of short IPI than non-Hispanic White (NHW) women (4.4%). Adjusted odds ratios for PTB and short IPI were 1.64 (95% CI 1.54, 1.76) for NHW and 1.49 (1.34, 1.65) for NHB. Using within-mother analysis did not produce substantially different results.
Conclusions:
Short IPI is associated with PTB but does not explain risk disparity between NHWs and NHBs.
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