Short interpregnancy interval as a risk factor for preterm birth in non-Hispanic Black and White women in California

Objectiveshort 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 designusing 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.resultsnhb 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.conclusionsshort ipi is associated with ptb but does not explain risk disparity between nhws and nhbs.