Purpose: Many women report disturbed sleep during pregnancy, but its impact on clinical outcomes remains unknown. This study examined subjective sleep quality and daytime sleepiness in relation to preterm birth. Methods: A convenience sample of 220 pregnant women completed the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), and the Perceived Stress Scale (PSS) during the second trimester. Women who had preterm and full-term births were compared on these measures. Results: The preterm birth rate of the sample was 14.6 %. Sleep latency, the period from lights out to sleep onset, was significantly longer in the preterm group, which also reported a tendency to use more sleep medications, but had lower PSQI daytime dysfunction scores. Perceived stress did not differentiate preterm and full-term groups. Conclusion: Disturbed sleep in pregnancy may be associated with preterm birth. Future studies should examine specific physiological factors that underlie this increased vulnerability.