<![CDATA[Background: Sleep and physical activity play critical roles in maternal and fetal health during pregnancy. However, longitudinal changes in these behaviours remain understudied. This study aimed to investigate sleep and physical activity behaviours across pregnancy using objective measures. Subjects and Method: A longitudinal observational study was conducted in Australia from January 2019 to November 2020. Pregnant women in their first trimester (≤14 weeks gestation) were recruited via Facebook using convenience sampling. Fourteen participants were continuously monitored throughout all three trimesters using wrist-worn Fitbit Charge 2 devices. Sleep outcomes included total sleep duration (hours/night) and number of nightly awakenings after sleep onset, while physical activity was measured as total daily minutes. Gestational progression (trimester and day of pregnancy) served as the independent variable. Data were analyzed using linear regression and linear mixed-effects models. Results: Sleep duration significantly declined across pregnancy (p<0.001). No significant difference was observed between the first (Mean= 6.93 hours; SD= 2.22) and second trimesters (Mean= 6.73 hours; SD= 1.94), but a marked decrease occurred in the third trimester (Mean= 4.95 hours; SD= 2.56), with an average reduction of 1.5 hours per night compared to the first trimester (p<0.001). Regression analysis confirmed a progressive daily decline in sleep duration (β=-0.013, p<0.001). Nightly awakenings averaged (Mean= 18.6; SD= 15.3) and decreased over time (β=-0.051, p<0.001). Mean daily physical activity was 114.84 minutes, predominantly light intensity (94.5%), with minimal moderate (3.78%) and vigorous activity (1.72%). Physical activity increased modestly across trimesters (p=0.046), with a significant difference of approximately 16.7 minutes per day between the first and third trimesters (p=0.040). Conclusion: Sleep duration declines progressively during pregnancy, particularly in the third trimester. Although overall physical activity increases, it is largely dominated by light-intensity activity, with low participation in moderate and vigorous levels. Given the importance of adequate sleep and appropriate physical activity for maternal and fetal health, these findings highlight the need for targeted interventions to improve sleep and promote adherence to recommended activity guidelines during pregnancy.]]>
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