The fight for good sleep is no joke when you are pregnant, especially during the last trimester, when heartburn and just getting comfortable make it extra difficult to fall asleep and to stay asleep. Many pregnant women turn to melatonin to help them fall asleep faster and have more sleep hours and since melatonin is a natural hormone made by our brains, it seems like a simple, harmless and effective way to catch some extra zs without using a chemical sleeping aid that could harm your unborn baby.

But before you reach for this popular supplement, make sure you have all the information you need to make an informed decision. We’ve done a deep dive into all the data out there on pregnancy and melatonin, so you can peruse the most important info. Keep reading for the 5 crucial things to know about melatonin and pregnancy.

1. The body naturally produces more melatonin during pregnancy

Despite the fact that you might not be sleeping very well, you might be surprised to know that your melatonin level naturally increases during pregnancy. The MGH Center for Women’s Mental Health reports that, “during pregnancy, night-time concentrations of melatonin increase steadily after 24 weeks of gestation” and that “melatonin receptors are present throughout the developing foetus from the earliest stages” suggesting that it “plays an important role in training circadian rhythms in the developing foetus.”

It is also interesting to note that the ovaries and placenta trigger this higher production of melatonin and it increases even more after 32 weeks, as the body gets ready for labour. According to healthline, melatonin works together with oxytocin to promote labour and delivery and even after birth, babies continue to get melatonin from the mother during night-time breastfeeding.

Why is this important? Because if your melatonin levels are already naturally higher when pregnant and you take a melatonin supplement, you are raising your melatonin to a level much higher than your body normally experiences. While some doctors feel that this isn’t harmful, there is not a lot of research in this subject area, so it is something to consider before reaching for that supplement.

2. There is very little research in the subject area of melatonin and pregnancy

As we mentioned above, there isn’t a lot known about the long-term effects on a developing foetus’ brain when the mother has taken melatonin while pregnant. There also isn’t a lot known about the safety of breastfeeding mothers taking melatonin.

While many doctors suggest that short-term melatonin is harmless, others say that “natural isn’t always safe” and that it is best to avoid all but the absolutely necessary supplements while pregnant.

Many of the studies that have been done in this subject area have been done on animals, not humans, and so there isn’t a lot known about how melatonin affects foetal development or if it can protect or harm the baby in utero. Keep this in mind when you are deciding whether or not a melatonin supplement is right for you.

3. There is conflicting research

Another problem is that the research that has been done is often conflicting in its conclusions. While some studies say that melatonin is harmless to a baby and can even be beneficial, others say that it can be dangerous. For example, one study showed that taking melatonin while pregnant can reduce the risk of pre-eclampsia (high blood pressure) and preterm birth and intrauterine growth retardation (IUGR). However, this was an animal study and more research is needed in humans.

Other studies have shown that taking melatonin can contribute to low birth weight and an increased risk of infant mortality. In one particular study, pregnant rats were given melatonin from day one of pregnancy through to day 21 postpartum.

At the end of the study, the rats who had the melatonin supplements showed less weight gain during pregnancy and their litter size was significantly smaller. The baby rats whose mother had melatonin were also of significantly lower body weight and there was an increase in mortality with these same baby rats, yet the cause of the death was not clear.

Again, this study was done on rats and more research is needed in humans but it presents some cause for concern and suggests that maybe melatonin supplements aren’t safe for pregnant women.

4. Melatonin may have an effect on the reproductive system before pregnancy

Melatonin truly does affect almost every system in the body, including the reproductive system. There is evidence to suggest that melatonin can even help those trying to conceive, by “having a beneficial effect on fertilization rates and embryo quality”.

As you may already know, melatonin acts as an antioxidant in the body and these positive effects on conception could be due to its antioxidative qualities. If melatonin can reduce free radical damage throughout the body, including in the ovaries, it stands to reason that healthy melatonin levels are necessary for healthy egg production. There are other studies that show that in vitro fertilization can be more successful if the woman takes melatonin.

But what does this have to do with women that are already pregnant? Well, there is one ongoing trial on humans that will include 60 women that seeks to determine the effect of melatonin on brain injury in babies, when melatonin is given to the mothers long before birth (before 28 weeks of pregnancy). This trial seeks to determine what dose of melatonin can reduce brain injury in babies, particularly cerebral palsy, which is the most common physical disability in childhood.

This study would also demonstrate, presumably until what week of pregnancy melatonin is most effective, or safe, if at all, or at least give some insight into this subject area when it comes to humans.

5. Melatonin is not regulated by the FDA

Melatonin is not considered a drug, but instead a natural supplement, and so you’ll find it in the same place on the drugstore shelf as vitamins and herbal remedies. But this doesn’t necessarily make it safe. Because melatonin is not regulated by the FDA, there is no standard recommended dosage and no recommended daily allowance for adults, whether they are pregnant or not.

The recommended dosage for pregnant women varies depending on the source and can go from nothing at all to multiple times the natural amount found in the body. In fact, the standard dosage of melatonin found in the drugstore (1-3mg) raises the body’s melatonin levels up to 20 times the normal level.

Is this suggesting that every beneficial supplement and herbal remedy has to be regulated by the FDA? Of course not and there are plenty of herbal remedies that have been used for centuries around the world that are not regulated by the FDA. But, what
it does mean is that since there currently isn’t a pharmaceutical company that can benefit from producing melatonin and since pharmaceutical companies often fund major studies on the long-term effects of drugs, there just isn’t a lot known about melatonin as a supplement.

Melatonin can be produced synthetically or it can be derived from bovine or other animal sources and the label doesn’t have to tell you where it came from, which is also something to consider if you want to bring ethics into the equation or if you are a vegetarian.

Final Thoughts

One way to avoid all the controversy and questions surrounding melatonin and pregnancy is to just raise your melatonin levels naturally without a supplement. There are many ways to do this, but here are a few tips:

  • Try to get at least eight hours of sleep a night, during the darkest hours of the night.
  • Before you go to bed, wind down by doing calming activities like having a bath, reading in bed or meditating.
  • Don’t take your handheld devices into bed with you. The blue light can disrupt your melatonin levels.
  • Eat foods that contain magnesium, which helps raise the melatonin levels in your body.
  • Avoid sugar and caffeine, especially before bed.

Let’s face it, pregnancy and sleep are just two things that don’t always go together, but by doing even a few of these easy things above, you are giving your body the best chance at maintaining a natural level of melatonin without a supplement, which may be the best idea until we know more about this hormone and its effects on pregnancy.

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