Melatonin: Pregnancy’s Overlooked Powerhouse
While many of us recognize melatonin as a “sleep hormone”, its power lies far beneath the surface of bedtime. In fact, melatonin is involved in antioxidant protection, immune function, reproductive health, healthy pregnancy, and fetal development. Follow along on this journey as we reveal just how powerful melatonin is, and how you and your baby benefit from it!
Melatonin is a neuroendocrine hormone–neuro referring to the brain and nervous system and endocrine referring to the body’s chemical signaling between organs. Melatonin is first produced in the brain’s pineal gland. When released, it follows a steady, daily pattern. Levels are low during the day, but as evening approaches, and the eyes start to recognize darkness, it triggers the release of melatonin, telling the body to wind down for sleep.
The less commonly known fact about melatonin is that it is vital for ovulation, fertilization, implantation, and pregnancy! Melatonin is a potent antioxidant, which means it protects egg cells (oocytes) and young embryos from oxidative stress during these fragile stages. It also supports egg maturation, helping prepare eggs for healthy and successful fertilization. It’s no coincidence that the ovarian follicles contain high levels of melatonin, especially during the luteal phase. Both the ovaries and placenta express melatonin receptors that aid in reproductive signaling.
Fertilization through Pregnancy
The fertilized egg must travel to the uterus for implantation. No surprise — melatonin steps in here, too! Melatonin helps regulate the body's inflammatory response, supporting the right amount of immune activity while helping prevent excessive inflammation that can damage cells and tissues. This creates an environment that is more favorable for implantation and early growth.
As the baby grows, it relies on nutrients from mom to thrive, and this is where the placenta comes in. The placenta acts as a lifeline to baby transferring nutrients, oxygen, and hormones while removing waste products. Here’s where the magic of melatonin truly comes into play! Melatonin produced by mom helps set the baby’s circadian rhythm in utero even before baby ever experiences full sunlight or darkness. Melatonin also contributes to REM sleep, which is associated with rapid brain growth and neural development.
Melatonin levels begin to rise during the first trimester of pregnancy and surge further during the second trimester. This increase is likely due, in part, to the growing demands of pregnancy and melatonin production by the placenta. Levels continue climbing throughout the third trimester, reaching their highest concentrations around labor before dropping abruptly after delivery. This rapid decline occurs because the placenta—which produces a significant amount of melatonin during pregnancy—is no longer present.
Birth & Postpartum
Melatonin reaches some of its highest levels during labor, making the uterine muscles more sensitive to oxytocin. Oxytocin is responsible for stimulating and coordinating contractions. Together, these hormones work in synergy to help labor progress effectively.
So, how does melatonin impact the newborn? One of its most important roles is protecting against oxidative stress. Since a newborn’s immature system experiences a sudden increase in oxygen exposure at birth, it needs an extra layer of protection. These effects may contribute to improved neurological outcomes. To aid in stress regulation, melatonin also interacts with the hypothalamic-pituitary-adrenal (HPA) axis, helping moderate cortisol responses.
Melatonin even plays a starring role in breastfeeding. Because it is naturally present in breast milk, melatonin helps regulate a baby’s developing circadian rhythm. Interestingly, breast milk contains higher levels of melatonin at night, helping provide time-of-day cues to the infant. Melatonin also interacts with the gut-brain axis and may influence the developing gut microbiome. There is even an association between breastfeeding and lower rates of colic. Researchers speculate that melatonin may contribute by relaxing smooth muscle, influencing gut motility, and reducing inflammation.
What now?
It’s clear that melatonin contributes to a healthy pregnancy and supports a newborn’s transition into the world. So much of our lifestyle influences melatonin production, including sleep habits, exposure to blue light, stress levels, and even the foods we eat. At Embody Nutrition & Wellness, we specialize in supporting women during the crucial stages of preconception, pregnancy, and postpartum. Let us help you become the healthiest and happiest version of yourself as you welcome your baby!
Written by Leah Wilson, Embody Intern
References
The Role of Melatonin in Pregnancy and the Health Benefits for the Newborn
Verteramo R, Pierdomenico M, Greco P, Milano C
Biomedicines. 2022 Dec 14;10(12):3252. doi:10.3390/biomedicines10123252
https://pmc.ncbi.nlm.nih.gov/articles/PMC9775355/
Outline of Changes in Cortisol and Melatonin Circadian Rhythms in the Security Guards of Shiraz University of Medical Sciences
Zamanian Z, Dehghani M, Hashemi H
Int J Prev Med. 2013 Jul;4(7):825-830.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3775223/
Is Melatonin the “Next Vitamin D”?: A Review of Emerging Science, Clinical Uses, Safety, and Dietary Supplements
Minich DM, Henning M, Darley C, et al.
Nutrients, 2022 Sep 22;14(19):3934. doi:10.3390/nu14193934
https://pmc.ncbi.nlm.nih.gov/articles/PMC9571539/
