Medically Reviewed

Melatonin during Pregnancy: Does it Work and is it Safe?

Sleep problems are very common during pregnancy. More research is needed to determine whether melatonin is a safe treatment for pregnant people.

Can you take melatonin while pregnant? The Research

If you’re pregnant, maybe you’ve noticed that you’re having some difficulty sleeping. According to the research, you’re far from alone. More than 72% of pregnant people experience waking up frequently throughout the night. By the third trimester, 97% of pregnant people end up experiencing sleep pattern disruptions.

So, naturally, you might wonder what can be done about this. Sleep is crucial to your overall health. Could a melatonin supplement be part of the solution?

Melatonin is a natural hormone produced by the pineal gland in your brain, and it helps you get to sleep. Melatonin supplements are a common and effective method for people experiencing sleep problems, including jet lag and disruptions to the circadian rhythm. When it comes to pregnancy, though, the research is somewhat limited. We will take a look at what we know so far.

Pregnancy and sleep issues

Temporary sleep issues are incredibly common during pregnancy – so much so that it would actually be unusual if you were pregnant and didn’t have some sleep issues. As mentioned above, disrupted sleep affects up to 97% of pregnant people by the third trimester. These sleep problems are caused by the hormonal, physiological, and physical changes that a person experiences during pregnancy.

Sleep, as you well know, is important for everyone’s health. Lack of sleep can lead to a host of health problems, including drowsiness, irritability, and can even impact immune function. For a pregnant person, getting good sleep can be especially important, as more and more is being asked of your body. In fact, sleep deprivation during pregnancy has been associated with potential negative outcomes. Finding a way to get good sleep is a way to care for yourself and to care for the health of the child growing inside you.

Pregnancy and melatonin levels

Natural melatonin levels while pregnant

Studies show that melatonin levels rise naturally around 24 weeks of pregnancy and then again around 32 weeks of pregnancy. Since a human’s pineal gland – the part of the brain that produces melatonin – doesn’t develop until after birth, your unborn child relies on the melatonin that your body is producing. Indeed, melatonin receptors are present in the embryo and fetus from the early stages of pregnancy. It’s probable that your melatonin supply helps develop your unborn child’s circadian rhythm, as well as affecting the fetus’s neurological development.

Since melatonin levels tend to rise naturally throughout pregnancy, it’s possible that a melatonin supplement would result in your body having too much melatonin. It’s no doubt that sleep can be challenging during pregnancy, but it seems that melatonin isn’t the issue. Disrupted sleep is most likely due to other factors, like physical discomfort and other hormonal changes.

Changes in melatonin levels throughout pregnancy

Natural melatonin levels undergo significant changes in pregnant people compared to non-pregnant people. As pregnancy progresses, these levels continue to increase, reaching their peak in the third trimester. Within 24 hours after delivery, though, melatonin levels sharply decrease, reverting to pre-pregnancy levels.

The role of placenta in melatonin during pregnancy

The placenta’s contribution to melatonin levels during pregnancy is a subject that’s sparking interest. The placenta contains enzymes that are needed to produce melatonin in the body, but the exact extent to which this occurs is not well understood. However, since melatonin levels increase throughout pregnancy and drop off sharply within 24 hours after delivery, researchers suspect that the placenta plays a major role in the increasing melatonin levels.

The potential impact of melatonin on fetal development

Melatonin’s impact on fetal development is complex and multifaceted. First, let’s start by discussing endogenous melatonin, which is the melatonin that the body naturally produces. Endogenous melatonin regulates vital functions such as mitochondria activity, antioxidant-like responses, nervous system health, immune system responses, and healthy sleep and circadian rhythm balance. These benefits may set a foundation of support for healthy fetal development, pregnancy, and labor/delivery. In addition, endogenous melatonin is able to cross the placenta and is also present in breast milk, potentially supporting healthy oxidative responses in newborns.

As for exogenous melatonin, the form of melatonin from supplements, research is varied. A 2022 review of eight studies concluded that melatonin is “probably safe” during pregnancy and that no major safety concerns or adverse events occurred. More studies of exogenous melatonin supplementation during pregnancy are needed to measure for more specific outcomes, like fetal development.

A Cochrane review has stated the following: “It is possible that melatonin, given to a mother in pregnancy, can help protect her baby's brain.” These claims were based on animal studies that suggested that melatonin may be able to protect the developing human baby’s brain when given to the mother during pregnancy. There is one small clinical trial, consisting of 60 participants, that is currently examining this phenomenon; that study is still ongoing. More trials needed to test the validity of these claims.

A small study found that melatonin could possibly lengthen gestation in a group of participants who had preeclampsia (pregnancy related blood pressure issues), which is a major contributing factor to preterm birth. But this was a subset of people with a specific issue unrelated to melatonin’s typical use. These findings would need to be replicated in larger trials. In the short term, melatonin was deemed “safe” for the mother and fetus, but long-term effects remain unknown and untested.

An animal study has found melatonin to be unsafe in pregnancy, with negative impacts on maternal and fetal weight, as well as other concerns. However, humans are not rats and more recent research has not identified the same level of serious risks in humans. Still, this doesn’t mean that melatonin is automatically safe in pregnancy.

Interestingly, in preterm newborns, melatonin has been used to support healthy oxidative responses and better health outcomes. Still, only a medical provider can decide what is safe for your pregnancy or your baby.

Talking to your doctor about melatonin and sleep during pregnancy

It’s important to talk to your doctor before deciding to take a melatonin supplement during pregnancy. Your doctor can help you think through your sleep problems and prevent you from exposing yourself or your unborn baby to any potential harm.

What if I took melatonin before I realized I was pregnant?

If you’ve been taking a melatonin supplement and then you discover you’re pregnant, you likely have no cause for concern. A review of fifteen studies found that melatonin use during pregnancy is probably safe for humans. Once you know you’re pregnant, though, consider discontinuing the supplement until you talk to a doctor. While more clinical studies are on the way for pregnant people, for now, there is a lack of sufficient research.

Alternatives to melatonin during pregnancy

While melatonin itself may pose more questions than answers regarding its safety during pregnancy, there are several alternatives that can be explored to support sleep. These include natural options, lifestyle changes, and certain medications, all of which should be considered with care and under the guidance of a healthcare provider. Let's explore these alternatives in detail.

Natural alternatives to melatonin

Unfortunately, there are no natural sleep supplement alternatives that can be used during pregnancy. Magnesium supplements are sometimes used in pregnancy, but research has shown that they don’t necessarily improve common issues, such as leg cramps. Outside of pregnancy, data from NHANES has found that inadequate intake of magnesium and other micronutrients has been associated with shorter and poorer quality sleep, though these findings haven’t been trialed in pregnant individuals. Nonetheless, supporting adequate micronutrient intake is essential for a healthy pregnancy, and improved sleep may be an added positive outcome.

Lifestyle changes to improve sleep quality while pregnant

Sometimes simple lifestyle changes can be enough to improve sleep quality during pregnancy. Consider some of the following:

  • Reduce caffeine intake, especially later in the day
  • Practice good sleep hygiene by creating a dark, cool, quiet room environment
  • Limit blue light exposure from smart phones and television at least one hour before bed
  • Engage in regular physical activity, within medical guidelines
  • Use a pregnancy pillow or specific back and side support
  • Incorporate calming practices before bed such as meditation or breathing exercises
  • Avoid large meals before bed, since digestive upset can affect sleep
  • Keep a consistent sleep schedule and routine

Safe medications for sleep issues during pregnancy

Navigating the use of medications can be complicated since so many drugs aren’t safe during pregnancy. In order to provide some direction, medications are rated based on classes that indicate how safe they are in pregnancy. Let’s take a look at the five risk categories:

  • A: No risk in human studies
  • B: No risk in animal studies, but no adequate human studies available
  • C: Risk cannot be ruled out; animal studies demonstrate possible risk, human studies unavailable with evidence; benefits of drug may outweigh risk
  • D: Evidence of risk; studies in pregnant people have shown risk; but potential benefits of drug may outweigh risk
  • X: Contraindicated; studies in pregnant people have found risk and/or animal studies have shown fetal abnormalities

In addition to these categories, the FDA has added updated clinical guidelines known as the Pregnancy and Lactation Labeling Rule (PLLR), although physicians still tend to use the graded category classes.

There are rarely simple yes/no answers when it comes to assessing the safety of medicines during pregnancy; decisions must be made on a case-by-case basis, considering available evidence and individual patient needs. Many times the decision of whether the risks outweigh the benefits of certain drugs needs to be made by the patient and their doctor.

In rare cases, an OBGYN may suggest some medications to support sleep for pregnant people. When nausea or morning sickness affects sleep, doctors may also prescribe medications to support sleep. However, only a doctor can determine what is safe for each pregnant person since everyone has unique risk factors and pregnancy considerations.

The bottom line

Sleep is important to your health, especially during pregnancy. Melatonin could be part of helping you get better sleep, but more research is needed. Check with a doctor before starting a melatonin supplement. Even if you don’t take melatonin, there are other strategies that can help you get much-needed sleep.

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