MATERIALS AND METHODS: A total of 129 healthy blood donors and staffs of Penang General Hospital were recruited from June 2018-May 2019. Paired (morning and late-night) saliva samples were collected from individuals aged between 18 and 60 years old with no history of chronic medical illness. Salivary cortisol was assayed using electrochemiluminescence immunoassay technique. Non-parametric statistics were used for calculation of reference interval and 90% confidence intervals (90% CIs).
RESULTS: The reference interval for morning and latenight salivary cortisol was 2.09 - 22.63 nmol/L and <12.00 nmol/L, respectively.
CONCLUSION: The locally-derived adult reference intervals for morning and late-night salivary cortisol concentration was determined and varied with previous studies emphasising the need in establishing individual laboratory reference interval.
METHODS: Ten government maternal and child health clinics in Kuala Lumpur, Malaysia will be randomly selected. Sample size of 438 first-trimester pregnant women will be followed-up until the birth of their infant. Salivary melatonin and cortisol concentration among subsample will be determined using enzyme-linked immunosorbent assay. Data on sleep quality, psychological distress and morningness/eveningness chronotype of pregnant women will be collected using validated questionnaires. Pedometer will be used to measure 5-day physical activity data. Total gestational weight gain will be determined at the end of pregnancy. Utilization of 3-day food record is to capture meal timing and nutrient intake. All measurements will be done in 2nd and 3rd trimester. Birth outcomes will be collected through clinic records and Centers for Disease Control and Prevention (CDC) Neonatal questionnaire. Infants will be followed-up at 6 and 12 months old to obtain anthropometric measurements.
DISCUSSION: There is a growing recognition of the role of maternal circadian rhythm, which entrains fetal circadian rhythms that may subsequently have long-term health consequences. The present study will identify the effect of circadian rhythm on pregnancy outcomes and infant growth in the first year of life.
OBJECTIVES: The aim of this study was to investigate physiological and psychological aspects of mother-infant signaling during breastfeeding experimentally, testing the effects of a relaxation intervention on maternal psychological state, breast milk intake, milk cortisol levels, and infant behavior and growth.
METHODS: Primiparous breastfeeding mothers and full-term infants were randomly assigned to receive relaxation therapy [intervention relaxation group; n = 33 (RG)] or to the control group [n = 31 (CG); no relaxation therapy] at 2 wk postpartum. Both groups received standard breastfeeding support. Home visits were conducted at 2 (HV1), 6 (HV2), 12 (HV3) and 14 (HV4) wk to measure maternal stress and anxiety, breast milk intake and milk cortisol, and infant behavior and growth.
RESULTS: RG mothers had lower stress scores postintervention than the CG (HV3 ∆ = -3.13; 95% CI: -5.9, -0.3) and lower hindmilk cortisol at HV1 (∆ = -44.5%; 95% CI: -76.1%, -12.9%) but not at HV2. RG infants had longer sleep duration (∆ = 82 min/d; 95% CI: 16, 149 min/d) at HV2 and higher gains in weight and body mass index standardized deviation score than the CG infants (∆ = 0.76; 95% CI: 0.3, 1.22; and ∆ = 0.59; 95% CI: 0.09, 1.1, respectively). RG infants had a mean milk intake at HV3 that was 227 g/d higher than that of the CG infants (P = 0.031) after controlling for gender and milk intake at HV1.
CONCLUSIONS: The trial shows the effectiveness of a simple relaxation intervention for improving maternal and infant outcomes and identifies some potential signaling mechanisms for investigation in future and larger studies, especially in settings where mothers are more stressed, such as those with preterm or low birth weight infants. This trial was registered at clinicaltrials.gov as NCT01971216.