The human body is capable of incredible things. Often described as “the miracle of life,” pregnancy is by far one of the most awe-inspiring processes that the mammals can accomplish. At the same time, it can be a scary and fragile process. Many people who just find out they’re pregnant will instinctively be more mindful of their health, particularly with what they consume. Unfortunately, one of the common health-related struggles with pregnancy (as well as parenthood in general) is sleep difficulty. The combination of hormonal changes and later pregnancy discomfort can disrupt the natural circadian rhythms and ultimately not bode well for the next morning. Melatonin is a popular sleep supplement due to its effectiveness and the fact that melatonin is already a natural hormone released by our pineal glands¹. But is it safe to take melatonin while pregnant? 

Your body’s production of melatonin during pregnancy

Pregnancy actually causes a natural increase in melatonin production. Research has found that high levels of melatonin are produced by the ovaries and placenta during pregnancy, particularly at 24 weeks and again after 32 weeks². Melatonin levels are higher at night as the natural sunlight diminishes and triggers the pineal gland to begin releasing melatonin. Researchers are finding that the body’s production of melatonin during pregnancy serves several benefits to both your body and the developing fetus.

Benefits of your natural production of melatonin to your body:

Aside from improving your circadian sleep cycles at night, melatonin has been found to produce several benefits to your body. These benefits include:

1. Increased fertility³ - More studies are still needed before melatonin can be safely recommended in clinical practice for women undergoing assisted reproductive technology (ART), however the rationale behind the idea that melatonin might increase fertility is that melatonin “protects cells from oxidative stress by acting as a free radical scavenger and by stimulating antioxidant enzymes.”³  Basically, melatonin is known to protect our cells on some level. Researchers have been studying melatonin supplementation during controlled ovarian stimulation with the hopes of improving the reproductive outcomes of anyone undergoing ART.

2. Improved functioning of the placenta⁴ - One study looked at maternal treatment of undernourished pregnancies in rats by using melatonin. Researchers found that the rats who received melatonin treatment ended up with improved placental efficiency and the increased expression of placental nutrients critical for fetal development. This means that the placenta was doing a better job at helping the fetus develop despite undernourishment during pregnancy. We cannot say with certainty that these findings are applicable to human pregnancies, of course, and more human studies must be completed prior to safely recommending melatonin treatment during pregnancy.

3. Reduced risk of pre-term birth (as seen with animal trials)⁵ - Preterm delivery can lead to a host of health issues and increased risk of mortality. There is currently no go-to therapy or preventative measures that are known to guarantee full-term pregnancies. One potential cause of preterm birth is infections that enter the amniotic fluid. Researchers have assessed the effect of melatonin in mice and its impact on fetal development duration. This study found that 50% of the mice who were given a pellet of melatonin on day 14 of their pregnancy did not experience preterm birth despite being injected with a bacterium known to cause preterm labor, whereas 100% of the mice who received the same bacteria without melatonin went into preterm labor. This may be one of the reasons why the uterus and placenta increase melatonin production during pregnancy. Researchers are continuing to investigate the possibility of using melatonin as a therapeutic tool to prevent preterm labor and to reduce newborn mortality rate.

Melatonin and the fetus

Now that we have a better understanding of how melatonin may affect the body before and during pregnancy, let’s talk about how melatonin may affect the developing fetus.

Brain development⁶

Melatonin is neuroprotective. According to one research review, melatonin offers protective effects on fetal brain development⁶. Fetal brain is susceptible to variations in oxygen levels and stress that can cause issues during brain development. Since melatonin has strong antioxidant features, meaning it can help protect cells from damage, researchers have suggested that melatonin should be considered as a treatment method against fetal brain injury.

Fetal growth^7,8

As expecting parents monitor their child’s fetal development, the most talked-about and easily observed observation is fetal growth. It’s estimated that about 5% of pregnancy complications are associated with fetal growth restriction⁷. This could lead to short-term and long-term effects such as reduced oxygenation, inflammation, and possibly cerebral palsy. Melatonin and its effects on fetal hypoxia and fetal growth restriction has been investigated in lambs⁸. Researchers found that maternal administration of melatonin in pregnant sheep improved both neurodeveloment and fetal growth in newborn lambs- all because of melatonin’s neuroprotective potential.

Autism ⁹

Autism Spectrum Disorder (ASD) is a spectrum of different ways of thinking, feeling, and behaving. While many people who are Autistic are independent and successful (like Alice in Wonderland’s author Lewis Carrol, or director Tim Burton), many others may find communication and other daily functions much more challenging. Researchers are considering melatonin deficiency as a potential factor that increases the chances of developing autism. One study looked at the melatonin levels of 60 mothers of Autistic children and compared these levels to mothers of neurotypical children, and they found that parental melatonin levels of Autistic children were indeed significantly lower than parents of neurotypical children. The authors indicate that this study does need to be duplicated on a larger scale prior to generalizing these findings, however.

What about melatonin supplements during pregnancy?

Despite the benefits of our body’s natural production of melatonin during pregnancy, there is still no sufficient evidence to indicate that melatonin supplements are either safe or unsafe during pregnancy. While this is not the answer anyone wants to hear, it’s still encouraged for pregnant parents to speak with their physician about melatonin if sleep deprivation is taking over. There is no exact dose that’s recommended, although 1-3 mg is the typically recommended dose of melatonin (which increases our body’s natural melatonin levels 20 times your normal level). Knowing that melatonin has neuroprotective elements and is produced by the placenta and ovaries during pregnancy may be promising hints that melatonin supplements are not as harmful during pregnancy as many might think. However, it’s wise to understand that not enough research on humans currently exists to confidently say one way or the other that increasing the melatonin supply in your bloodstream is in fact healthy.

The big takeaway? Know that your body is natural producing melatonin, particularly if you are pregnant, but speak with your physician before you decide to increase that melatonin in your body with supplements.

 

REFERENCES

1. Aulinas A. Physiology of the Pineal Gland and Melatonin. [Updated 2019 Dec 10]. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. 
2. Voiculescu, S E et al. “Role of melatonin in embryo fetal development.” Journal of medicine and life 7,4 (2014): 488-92.
3. Seko, Ludimila M D et al. “Melatonin supplementation during controlled ovarian stimulation for women undergoing assisted reproductive technology: systematic review and meta-analysis of randomized controlled trials.” Fertility and sterility 101,1 (2014)
4. Richter, Hans G et al. “Melatonin improves placental efficiency and birth weight and increases the placental expression of antioxidant enzymes in undernourished pregnancy.” Journal of pineal research 46,4 (2009): 357-64.
5. Domínguez Rubio, Ana P et al. “Melatonin prevents experimental preterm labor and increases offspring survival.” Journal of pineal research 56,2 (2014): 154-62.
6. Sagrillo-Fagundes, Lucas et al. “Melatonin in Pregnancy: Effects on Brain Development and CNS Programming Disorders.” Current pharmaceutical design 22,8 (2016): 978-86. doi:10.2174/1381612822666151214104624
7. Alers, Nicole O et al. “Antenatal melatonin as an antioxidant in human pregnancies complicated by fetal growth restriction--a phase I pilot clinical trial: study protocol.” BMJ open 3,12 e004141. 23 Dec. 2013, doi:10.1136/bmjopen-2013-004141
8. Supramaniam VG, Jenkin G, Loose J, et al. Chronic fetal hypoxia increases activin A concentrations in the late-pregnant sheep. BJOG Int J Obstet Gynaecol. 2006;113:102–109
9. Braam, W., Ehrhart, F., Maas, A., Smits, M. G., & Curfs, L. (2018). Low maternal melatonin level increases autism spectrum disorder risk in children. Research in developmental disabilities, 82, 79–89.

 

Last updated July 20, 2021 by Matthew Hermann