Fertility treatment increases the risk of preterm birth independent of multiple gestations

Objective: To investigate the complex interplay between fertility treatment, multiple gestations, and prematurity. Design: Retrospective cohort study linking the national Center for Disease Control and Prevention infant birth and death data from 2014 to 2018. Setting: National database from Center of Disease Control and Prevention. Patients: In total, 19,454,155 live-born infants with gestational ages 22–44 weeks, 114,645 infants born using non IVF fertility treatment (NIFT), and 179,960 via assisted reproductive technology (ART). Intervention: Noninvasive fertility treatment or ART vs. spontaneously conceived pregnancies. Main Outcome Measures: The main outcome assessed was prematurity. Formal mediation analysis was conducted to calculate the percentage mediated by multiple gestations. Results: Newborns born using NIFT or ART compared with those with no fertility treatment had a higher incidence of multiple gestation (no fertility treatment = 3.0%; NIFT = 24.7%; ART = 32.7%; P