Melatonin Safety in Pregnancy
Melatonin appears to be safe for use during pregnancy based on available human evidence, and may even provide protective benefits for both mother and fetus.
Safety Profile
Current human studies suggest melatonin use during pregnancy is probably safe, contrary to earlier concerns based on animal research. 1 The evidence from clinical trials using exogenous melatonin during pregnancy has not identified major safety concerns or adverse events. 1
Key Safety Findings:
No major adverse events reported: Clinical trials examining melatonin use during pregnancy have not demonstrated significant safety concerns. 1
Physiological role in pregnancy: Melatonin is naturally produced by both the maternal pineal gland and the placenta itself (possibly in mitochondria), suggesting it plays an essential physiological role during gestation. 2
Crosses placenta freely: Maternal melatonin enters fetal circulation without alteration, providing photoperiodic information to the fetus—this is a normal physiological process. 3
Increasing levels during pregnancy: Nighttime serum melatonin concentrations naturally increase toward the end of pregnancy, indicating the body's own recognition of its importance. 3
Potential Benefits During Pregnancy
Melatonin functions as a powerful antioxidant and anti-inflammatory agent in the placenta, which may protect against common pregnancy complications. 4
Protective Mechanisms:
Reduces oxidative stress: Acts as a free radical scavenger to maintain placental integrity throughout gestation. 4
Anti-inflammatory effects: Regulates immune homeostasis during early and late gestation, which is critical for accommodating fetal development. 4
May prevent pregnancy complications: Experimental evidence suggests melatonin supplementation reduces the frequency or severity of stillbirth, recurrent fetal loss, preeclampsia, fetal growth retardation, premature delivery, and fetal teratology—all conditions involving elevated oxidative stress. 2
Protects against circadian disruption: Melatonin's circadian rhythm synchronizing actions may overcome consequences of chronodisruption during pregnancy, which can negatively impact fetal health. 2
Clinical Context
The collective idea that melatonin supplements should be avoided during pregnancy is outdated and not supported by current human evidence. 2 While randomized controlled trials specifically examining melatonin for sleep disorders during pregnancy are lacking 1, the available clinical data from various studies do not suggest harm.
Important Considerations:
Prevalence of use: Large health administrative database surveys show approximately 4% of pregnant populations use exogenous melatonin, indicating real-world acceptance. 1
Non-toxic profile: Melatonin is an endogenously-produced molecule with high bioavailability and little to no toxicity. 2, 5
Essential for successful pregnancy: Evidence suggests melatonin appears essential for successful pregnancy outcomes. 3
Practical Recommendation
Melatonin can be considered safe for use during pregnancy when clinically indicated, particularly for sleep disorders or when its antioxidant/anti-inflammatory properties may benefit maternal-fetal health. The evidence supporting safety in humans outweighs theoretical concerns derived from animal studies. 1 Given its physiological role in normal pregnancy and lack of documented harm in human studies, melatonin should be given serious consideration as a supplement during pregnancy. 2