Rest-activity patterns and saliva cortisol rhythms during gestational weeks 22 and 32 and postpartum week 1

<p>Study was conducted to determine if there was evidence for a relationship between 24 h rest-activity and saliva cortisol rhythms with maternal-fetal health indicators. Primiparous women wore a wrist actigraphy device for a week to record activity during gestational weeks 22 (G22; <em>n </em>= 50) and 32 (G32; <em>n </em>= 46) and postpartum week one (PPW1; n=39). Participants also collected saliva samples every 4 hr over a 24 hr period during G22 (n=22), G32 (n=20) and 24-48 hr postnatal (n= 20), and cortisol concentrations were measured with ELISA. Circadian rhythmicity was assessed using autocorrelation coefficient (<em>r</em>24) and cosinor analysis.  Blood glucose levels, body mass index (BMI), gestational disease data, and gestational age of infant at birth were abstracted from medical charts. Mean <em>r</em>24, mesor (mean) and amplitude of activity decreased between G22 and G32, and G32 and PPW1 (<em>p < </em>.05).  Cortisol rhythms were not different between G22 and G32, however area under the curve (AUC) and mesor were decreased (<em>p < </em>.05) between G32 and 24-48 hr postpartum. More robust rest-activity rhythms during G32 were positively (<em>p</em>=0.003) associated with gestational age of infant at birth.  Time of cortisol peak (acrophase) during G22 was related with acrophase of activity (<em>r</em>=0.66; <em>p</em> = 0.001) and blood glucose levels (<em>r</em>= 0.58; <em>p</em>=0.006).  During G22, minutes of wake after sleep onset was positively related to cortisol mesor and AUC (<em>p </em><0.05). Across all three time points <em>r</em>24 of activity was related with cortisol amplitude (<em>r</em>=0.33; <em>p</em>=0.01). The association of less robust activity rhythms with earlier gestational age of infant at birth supports the potential that circadian system disruption is linked to maternal-fetal health outcomes. Further investigations are needed to understand the interaction among rest-activity and the metabolic-hormonal system during pregnancy and their association with maternal-fetal health outcomes.</p>

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