Dysregulation of diurnal salivary cortisol production is associated with spontaneous preterm delivery: a pilot study.

OBJECTIVES: The purpose of this study was to evaluate whether the diurnal fluctuation of salivary cortisol and its overall diurnal secretion are associated with the length of gestation in patients who were admitted to the hospital with an assigned diagnosis of possible preterm labor (PL) at a gestational age of 28-33 weeks. METHODS: In 22 patients, maternal saliva samples were collected for a cortisol assay 4 times per day (8 AM, 12 AM, 4 PM and 8 PM) on day 4 and day 6 after antenatal corticosteroid prophylaxis to prevent neonatal respiratory distress syndrome. RESULTS: Eight patients who ultimately delivered before term (32.6 ± 1.7 gestation weeks) showed an inverted fluctuation of salivary cortisol on both days 4 and 6, morning cortisol levels being significantly lower than evening levels. In contrast, in 14 patients who delivered at term (39.5 ± 0.6 gestation weeks), the physiological diurnal fluctuation of salivary cortisol was maintained. In addition, a distinctive feature of women delivering before term was a significantly hampered salivary cortisol diurnal production measured on day 6. CONCLUSIONS: Corticoadrenal activity is dysregulated and anticipates very preterm delivery in women with an assigned diagnosis of possible PL.