Melatonin and pregnancy

What is melatonin?

Melatonin is a hormone made by the pineal gland. The pineal gland is a small gland in the brain which releases Melatonin in response to feedback from the superchiasmatic nucleus. Melatonin was first isolated in 1958 by American physician Aaron B. Lerner and colleagues at Yale University School of Medicine.

What does melatonin do?

Melatonin helps control your sleep and wake cycles. Melatonin is released at night in order to prepare your body to fall asleep. Every time you turn on the light at night, this turns down the production of melatonin. Melatonin generation by the pineal gland peaks during the nighttime hours, induces physiological changes that promote sleep, such as decreased body temperature and respiration rate. During the day, melatonin levels are low because large amounts of light are detected by the retina. Light inhibition of melatonin production is central to stimulating wakefulness in the morning and to maintaining alertness throughout the day. Melatonin has antiageing properties. For example, it acts as an antioxidant, neutralising harmful oxidative radicals, and it is capable of activating certain antioxidant enzymes. Melatonin production gradually declines with age, and its loss is associated with several age-related diseases. Melatonin also plays a role in modulating certain functions of the immune system.

Animal studies have also demonstrated the importance of melatonin in foetal development. During pregnancy, night-time concentrations of melatonin increase steadily after 24 weeks of pregnancy. Melatonin receptors are present throughout the developing foetus from the earliest stages. There is evidence that melatonin is neuro-protective and plays an important role in training Circadian Rhythms  in the developing foetus; however, melatonin may have other important actions outside of the brain.Very small amounts of it are found in foods such as meats, grains, fruits, and vegetables. You can also buy it as a supplement. Melatonin is also sold over the counter as a dietary supplement and is a popular natural remedy for sleep problems. The dose used in most melatonin preparations is higher than what the body normally produces. A typical dose of melatonin (1 to 3 mg) elevates blood melatonin levels up to 20 times normal levels.

Research now suggests that melatonin is an important hormone in many physiological processes including fertility and foetal development.

Can Melatonin Act as a Fertility Aid?

A study at the University of Texas Health Centre in San Antonio suggests that healthy melatonin levels are necessary for optimal fertility. Eggs, like all cells in the human body, are exposed to free radicals that can cause DNA damage. Melatonin actually acts as an antioxidant in the ovaries, removing free radicals and preventing cellular damage.

Because healthy egg production is the first step to conception and a healthy pregnancy, these findings suggest that healthy melatonin levels are crucial to fertility. In fact, poor egg quality is one of the most common causes of infertility. Cellular biologist Russel J. Reiter, who oversaw this study, suggests that women who wish to conceive get eight hours of dark every night at roughly the same time to support a healthy circadian rhythm and melatonin levels.

Low Melatonin and Pregnancy

While the exact mechanism by which melatonin affects pregnancy is unknown, its necessity is clear. Pregnant women who have low melatonin levels are more likely to develop pre-eclampsia, intrauterine growth restriction, and other disorders than can have negative effects on both mother and child. In addition, women who receive melatonin supplements while undergoing IVF and throughout the rest of the pregnancy have healthier blastocyst development as well as more positive pregnancy outcomes.

Although scientists and physicians have known for years that healthy sleep cycles are important for healthy menstrual cycles, the importance of melatonin in fertility and pregnancy outcomes is new information that can be used to improve foetal and maternal health. A poorly regulated circadian rhythm can have negative effects on both fertility and pregnancy, effects that may be prevented with a simple melatonin supplement.

The Role of Melatonin in Fertility and Conception

Despite intensive research into fertility, modern medicine still offers only a few treatments for women who struggle to conceive or to remain pregnant. The recent findings on the importance of melatonin in conception and foetal development offer hope for women who plan to have children in the future. Maintaining a healthy circadian rhythm along with optimal melatonin levels may be the key to healthy pregnancy for many women. In the near future, women who wish to become pregnant may be asked to take melatonin in addition to folic acid and the other supplements recommended for healthy foetal development.

For pregnant women or those planning a pregnancy, it may be best to keep late-night light exposure to a minimum. According to a recent study, exposure to artificial light during the evening hours can seriously affect a woman’s reproductive health and even effect the health of her unborn child.


In women who are already pregnant, interference with melatonin levels may cause difficulties with the unborn child. If the foetus does not get the proper amount of melatonin from their mother, their biological clock can also become confused. This has been linked to behavioural problems such as attention deficit hyperactivity disorder (ADHD) or Autism in young children. There is a lot of research with regard to melatonin and pregnancy.  The placenta produces melatonin and this source of melatonin is thought to be important to a normal, healthy pregnancy.  In animal studies, it has been shown that supplementation with melatonin decreases the risk of pre-eclampsia , preterm birth and intrauterine growth retardation (IUGR).  Studies of melatonin in humans with IUGR and Pre-eclampsia are now in their earliest phases. Preliminary studies also suggest that melatonin supplementation may have a beneficial effect on fertilisation rates and embryo quality, likely due to a reduction in oxidative damage.

Hopefully these newer studies will soon yield more information on the reproductive safety of melatonin.