Diurnal salivary cortisol levels in postpartum mothers as a function of infant feeding choice and parity.
ABSTRACT Daily stress and sleep deprivation can influence the diurnal pattern of cortisol, which normally consists of high morning levels and a gradual decline throughout the day. While most individuals have consistent declining cortisol concentrations over days, others display either flat or inconsistent profiles. Postpartum mothers experience considerable home demands and sleep deprivation, yet, breastfeeding mothers perceive lower stress and reduced negative mood states compared to bottlefeeders. On the other hand, multiparity (having more than one child) is associated with reduced steepness in diurnal cortisol decline. Interestingly, no study to date has investigated the diurnal cortisol pattern and its stability across days in postpartum women as a function of their choice of infant feeding and parity. In this study, we measured salivary cortisol at four different time points during the day, on two non-consecutive days in first-time (primiparous) and second-time (multiparous) mothers at 5-20 weeks postpartum who were exclusively breastfeeding or bottlefeeding, and in non-postpartum mothers of young children (1-6 years). Among multiparous mothers, we found that cortisol levels in those who were bottlefeeding were higher than in breastfeeding mothers at both awakening and 1600 h. This effect remained significant after controlling for individual differences related to infant feeding choice, such as estradiol levels, education and income. No effect of infant feeding choice on cortisol concentrations was observed in primiparous mothers. While a consistent decline across days was common, some mothers presented a flat or inconsistent profile, a profile that was not associated with infant feeding choice or parity. Importantly, mothers with consistent declining profiles had the highest household income. Our findings suggest that although breastfeeding might promote a tighter regulation of diurnal basal cortisol secretion, in particular for multiparous mothers who are likely to be exposed to greater home demands and maternal responsibilities, some aspects of socioeconomic status such as income can also play a significant role in the stability of diurnal cortisol secretion across days.
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ABSTRACT: The neuropeptide oxytocin (OT) enhances maternal behavior and decreases blood pressure (BP) and stress responses in animals. Thus, the relationship of OT responsivity to BP in 14 breast- and 11 bottle-feeding mothers of infants was examined. Laboratory BP was assessed during baseline, speech preparation, active speech, and recovery on 2 days, 1 in which baseline and speech were separated by 10 min of baby holding and the other by no baby contact. Systolic BP reactivity to speech was lower after baby contact. Plasma OT change from baseline to speech after baby contact defined OT increase, minimal OT change, and OT decrease groups. OT increase mothers were primarily breast-feeders, and they had lower BP throughout both stress sessions and after baby feeding at home than OT decrease mothers, who also had greater BP reactivity to preparation and recovery. These results suggest that oxytocin has antistress and BP-lowering effects in humans.Health Psychology 12/2000; 19(6):560-7. · 3.83 Impact Factor
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ABSTRACT: Effects of past, current, and anticipated naturalistic daily stressors and of affect on salivary cortisol levels were examined. Participants (120) reported on stressors and affect 6 x /day in response to a preprogrammed wristwatch. Twenty min after each assessment they took a sample of saliva for cortisol analysis. Both the experience of a current stressor and anticipating a stressor were associated with increased salivary cortisol levels. Average increases in cortisol were relatively low, but inter-individual variability in this response existed. Stressors also were associated with lower positive affect and higher negative affect. Negative affect was associated with higher cortisol levels and positive affect was associated with lower cortisol levels. Daily stressors were not significant predictors of cortisol secretion when affect was controlled. Momentary assessment of daily stressors and of salivary cortisol proved to be a useful tool for examining psychoendocrinological processes in the natural environment.Psychoneuroendocrinology 06/1998; 23(4):353-70. · 5.14 Impact Factor
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ABSTRACT: The circadian secretory profiles of cortisol and growth hormone (hGH) in normal subjects are interrelated. Slight alterations in cortisol secretion are paralleled by similar ones of hGH secretion. Under physiological conditions an inhibitory effect of glucocorticoids on hGH secretion is more potent than a stimulatory one, while in normal young subjects the nychtohemeral cortisol and hGH levels are lower and higher, respectively, post 24 hours total sleep-deprivation, compared to baseline values. The aim of the present work was to further assess the qualitative characteristics of the 24-hour secretory patterns of these two hormones before and after 24 hours total sleep deprivation, by studying their non-linear profiles using fractal analysis. Cortisol and hGH were measured in 24-hour samples drawn from 10 healthy men (mean age SD: 24 +/- 1 yr, mean BMI SD: 25 +/- 1 kg/m2) before and after 24 hours total sleep deprivation. Twenty-four hour blood sampling was performed serially every 30 min the day before and the day after total sleep deprivation. The 24-hour hormone profiles were analyzed by Fourier spectrum, in order to verify periodicities; the corresponding attractors were drawn and their respective fractal dimensions were calculated using the box counting method. Diurnal cortisol levels before sleep deprivation gave rise to a fractal attractor with a D0 fractal dimension of 2.65 +/- 0.03, which decreased, post-sleep deprivation, to D0: 2.18 +/- 0.04. Growth hormone before sleep deprivation gave rise to a fractal attractor with a D0 dimension of 1.96 +/- 0.60, which increased to 2.24 +/- 0.60 post-sleep deprivation. These post-sleep deprivation changes of the fractal dimensions of cortisol and hGH, suggest that sleep deprivation leads to a more regular secretory profile of cortisol, while it tends to render hGH secretory profile less regular. Additionally, these changes of the fractal dimensions parallell the previously described quantitative overall changes of these hormones. The post-sleep deprivation decrease of cortisol fluctuation might reflect the mechanism by which sleep deprivation temporarily improves mood in melancholic depression, a condition associated with hyperactivity of the hypothalamic-pituitary-adrenal axis.Endocrine regulations 07/2002; 36(2):63-72.