Objective: Excessive daytime sleepiness is a frequently described phenomenon in pregnant women. The Epworth Sleepiness Scale (ESS) is a self reported standardized method of assessing sleep propensity and has been used extensively within pregnant populations. An elevated score is associated with sleep disordered breathing, as well as adverse obstetric and neonatal outcomes which may be indicative of a degree of placental dysfunction. Thus the aim of this study was to prospectively assess women using the Epworth questionnaire in conjunction with an ultrasound in both the second and third trimesters to determine if there was a difference in ESS scores across gestation and if a mid or late gestation assessment was correlated with Doppler ultrasound measures of fetal well-being. Materials and methods: Participants were prospectively recruited from a tertiary obstetric hospital and completed both an Epworth questionnaire and ultrasound examination in the second and third trimesters. Results: A total of 302 women took part in this cohort study. There was a statistically significant (p =.02) increase in ESS score across gestation. There was however no correlation identified in either the second or third trimester between ESS score and umbilical artery pulsatility index, middle cerebral artery pulsatility index, cerebroplacental ratio, umbilical venous flow, uterine artery pulsatility index or estimated fetal weight. A higher birth weight is associated with a higher ESS score in the second trimester but not in the third trimester (p =.03). Conclusions: Maternal sleep disordered breathing assessed by the ESS score is only correlated with increased birth weight but not with fetal Doppler parameters in low risk pregnancies.