Problem Interferon epsilon (IFNε) is a unique type I IFN that is expressed in response to sex steroids. Studies suggest that type I IFNs regulate inflammation‐induced preterm birth (PTB), but no study has examined the role of IFNε in human pregnancy. Method of Study We used stored vaginal swabs between 8 and 26 weeks of gestation from the Global Alliance to Prevent Prematurity and Stillbirth (GAPPS) biobank and measured IFNε by enzyme‐linked immunosorbent assay (ELISA). A total of 29 women with spontaneous preterm births, 34 women with medically indicated preterm births, and 134 women with term births were included. Secondary outcomes included a preterm birth with chorioamnionitis and preeclampsia with a preterm birth. Logistic regression calculated odds ratios (OR) and 95% confidence intervals (CI) adjusting for maternal age, race, body mass index, prior pregnancy complications, lower genital tract infections, chronic health conditions, and gestational age at blood draw. Results and Conclusions There was no significant association between IFNε and spontaneous preterm birth (ORadj 1.0, 0.8–1.3) or chorioamnionitis (ORadj 1.6, 0.7–3.5). A trend toward increased odds of medically indicated preterm birth (ORadj. 1.3, 1.0–1.8) was observed. This was likely due to elevated IFNε among women with preterm preeclampsia (ORadj. 2.0, 95% CI 1.3–3.2). While exploratory, our novel findings suggest that larger longitudinal studies of IFNε across human pregnancy may be warranted.