Chronic sleep loss during pregnancy as a determinant of stress: impact on pregnancy outcome

Short sleep duration, poor sleep quality, and insomnia frequently characterize sleep in pregnancy during all three trimesters. We aimed: (i) to review the clinical evidence of the association between conditions of sleep loss during pregnancy and adverse pregnancy outcomes; and (ii) to discuss the potential pathophysiological mechanisms that may be involved. A systematic search of cross-sectional, longitudinal studies using Medline, Embase, and PsychINFO, and MeSH headings and key words for conditions of sleep loss such as 'insomnia', 'poor sleep quality', 'short sleep duration', and 'pregnancy outcome' was made for papers published between January 1, 1960 and July 2013. Twenty studies met inclusion criteria for sleep loss and pregnancy outcome: seven studies on prenatal depression, three on gestational diabetes, three on hypertension, pre-eclampsia/eclampsia, six on length of labor/type of delivery, eight on preterm birth, and three on birth grow/birth weight. Two main results emerged: (i) conditions of chronic sleep loss are related to adverse pregnancy outcomes; and (ii) chronic sleep loss yields a stress-related hypothalamic-pituitary-adrenal axis and abnormal immune/inflammatory, reaction, which, in turn, influences pregnancy outcome negatively. Chronic sleep loss frequently characterizes sleep throughout the course of pregnancy and may contribute to adverse pregnancy outcomes. Common pathophysiological mechanisms emerged as being related to stress system activation. We propose that in accordance to the allostatic load hypothesis, chronic sleep loss during pregnancy may also be regarded as both a result of stress and a physiological stressor per se, leading to stress 'overload'. It may account for adverse pregnancy outcomes and somatic and mental disorders in pregnancy.