Melatonin Effects on a Fetus

Melatonin is a hormone produced by the body during darkness, primarily by the pineal gland in the center of the brain. Melatonin dietary supplements are commonly administered as a sleep aid. Melatonin plays an important role in the development of a fetus.

Entering the fetus

• Melatonin in a pregnant woman enters a developing fetus through the placenta. After entering the fetal circulation system, melatonin influences the circadian rhythms of the offspring.

Biological clock

• Melatonin receptors are numerous throughout fetal tissue. Scientists believe the presence of maternal melatonin significantly affects development of the offspring's biological clock.

Maternal effects

• In pregnant woman, naturally increased melatonin levels that are important to the development of the fetus may temporarily darken some parts of the skin, including the nipples, cheeks, forehead, nose, inner thighs and genitalia.

Regular levels

• About 90 days after birth, a newborn's melatonin levels become regular. The highest levels of melatonin in a newborn are found during the latter stages of nighttime sleep.

Caution

• Because scientists aren't sure whether melatonin affects fetal development in other ways, pregnant women are advised not to take melatonin supplements.