Psychobiological markers of stress in pregnancy: 6-sulfatoxymelatonin--a longitudinal study

Maternal stress, physical and psychological, has been associated with adverse pregnancy outcome. The pineal gland is a physiological transducer that reflects adrenergic input. In a recent pilot study, we found urinary 6-sulfatoxymelatonin, the melatonin metabolite, to be elevated after a women spent a day at work compared to levels after a day off work, a leisure day. To evaluate the value of melatonin as a marker of stress, we evaluate melatonin metabolite levels in 121 women, along with perceived anxiety levels and urinary cortisol. Urinary cortisol and maternal anxiety levels each were significantly higher after a work day compared to a leisure day p = .03 and p = .001, respectively. 6-Sulfatoxymelatonin was not significantly different between work and leisure. Changes in cortisol levels were correlated with changes in melatonin metabolite levels (r = .62, p = .001). There was no correlation between changes in anxiety between work and leisure and changes in 6-sulfastoxymelatonin. We found no correlation with 28 week 6-sulfatoxymelatonin or 28-week cortisol and birth weight or gestational age at delivery. Results of this study suggest that melatonin secretion may not be a valuable marker for stress in pregnancy.