Melatonin Content of Human Milk: The Effect of Mode of Delivery

Abstract

Objective: Cesarean section rates are increasing in developed countries and could be performed as an emergency or elective procedure. Our research aim was to determine whether elective cesarean section influences the melatonin content, the main circadian hormone, in human milk. Methods: Twenty-one women after vaginal delivery and 18 women after elective cesarean section were included. Only healthy mothers with normal newborns exclusively breastfed were recruited. Two samples of human milk were collected for each woman at three stages of lactation: colostrum, transitional milk, and mature milk; at each stage, one daytime sample and another nighttime sample were obtained. In total, 228 milk samples were studied. The melatonin content was analyzed by enzyme-linked immunosorbent assay. Results: Melatonin rhythmicity with higher melatonin content at night was maintained at each of the three stages of lactation, regardless of the type of delivery. A higher melatonin content was found in daytime colostrum after cesarean section with respect to colostrum obtained from mothers after vaginal delivery (30.3 pg/mL versus 14.7 pg/mL, p = 0.020). Melatonin content decreased progressively throughout the course of lactation in both groups. This decrease was significant when comparing transitional milk to colostrum in the cesarean group, both in the daytime (p = 0.016) and nighttime samples (p = 0.048). Conclusions: Cesarean section is associated with an increase in daytime colostrum melatonin. No difference was observed in mature milk with respect to vaginal delivery. Melatonin values in human milk decrease during the first month of lactation and circadian rhythmicity was observed irrespective of the mode of delivery.

Effect of pasteurization on melatonin concentration in human breast milk

“…The effect of pasteurization on hormones has been insufficiently studied, so it is worth extending the research to this issue because of their significant role. There are few studies concerning melatonin in breast milk soon after birth and the evolution of melatonin levels during the lactation period under normal conditions [16].…”

“…Such results are valuable information regarding the use of the pasteurization process for milk banks. At present, there are few scientific reports on the concentration of melatonin in human milk and its function for the proper development of the child [16,17,19].…”

“…However, scientific data suggest that the pasteurization process carried out in human milk banks may affect the concentration and activity of the food components [5,16,31,32]. Guerra et al (2018) examined the effect of Holder pasteurization (62.5 °C, 30 min.)…”

“…However, a mature circadian rhythm and response to the light/ dark cycle develops at 2-3 months of life. Thus, human milk is the only melatonin source in the perinatal period, and the infant melatonin level depends in this period on the circadian melatonin rhythm of the mother [16]. Some studies have attributed longer sleep time in breastfed infants compared with that in formula-fed infants to melatonin in breast milk, as no melatonin is detected in formula [17].…”

Melatonin in Early Nutrition: Long-Term Effects on Cardiovascular System

“…To some degree, the loss of placental melatonin after birth can be compensated for by the presence of melatonin in breast milk. Maternal milk contains melatonin, which exhibits circadian oscillations, with lower levels during the day and higher levels at night, reaching a peak of approximately 40 pg/mL [23]. As the endogenous rhythm of melatonin production is not attained until approximately three months after birth and continues to develop over the first six months of life, the importance of melatonin intake through breast milk in early life should be emphasized [24][25][26].…”