BackgroundChorioamnionitis (CAM) is a common risk factor for preterm births, resulting in several adverse outcomes. The association between infertility treatment and CAM is unclear. Therefore, this study examined the association between infertility treatment and CAM and described subsequent neonatal outcomes.MethodsThis population-based cohort study used data from the National Vital Statistics System Database. We included women who had a singleton live birth from January 1, 2016 to December 31, 2018. Women-infant pairs were stratified by infertility treatment, and the main outcome was a reported diagnosis of CAM in a checkbox format: clinical CAM or maternal temperature of > 38 °C. Multivariate logistic regression was used to examine the association between infertility treatment and CAM and the effect of infertility treatment on neonatal outcomes in women diagnosed with CAM.ResultsThe final sample comprised 10,900,495 woman-infant pairs, and 1.4% received infertility treatment. Compared with the natural conception group, women receiving infertility treatment had a significantly higher risk of CAM (adjusted odds ratio [aOR] 1.772 [95% confidence interval {CI}, 1.718–1.827]). Furthermore, newborns exposed to CAM had a higher risk of very low birth weight (VLBW) (aOR, 2.083 [95% CI, 1.664–2.606],P< .001), preterm birth (aOR, 1.497 [95% CI, 1.324–1.693];P< .001), neonatal intensive care unit admission (aOR, 1.234 [95% CI, 1.156–1.317];P< .001), and other adverse neonatal outcomes in the infertility treatment group compared with ones conceived naturally.ConclusionsThis study found that women who received infertility treatment had a higher risk of CAM. And CAM deteriorated neonatal outcomes in the infertility treatment group.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12884-023-05619-0.