Safety Status:
Trying to Conceive: Safe
Pregnancy: Avoid
Breastfeeding: Limited
What We Know: Melatonin is a hormone naturally produced by the pineal gland that regulates sleep-wake cycles. As a supplement, it’s commonly used for sleep disorders, jet lag, and shift work adaptation. Melatonin has antioxidant properties and also plays roles in reproductive physiology and seasonal breeding in some mammals.
For individuals trying to conceive, melatonin receives a “Safe” classification. Research published in the Journal of Ovarian Research and Fertility and Sterility suggests melatonin may support fertility in certain contexts, particularly in assisted reproduction, due to its antioxidant effects. Current human data do not show a negative impact on fertility. As an antioxidant, melatonin may improve egg quality and has been studied as an adjunct therapy during IVF treatment with some promising results.
During pregnancy, melatonin receives an “Avoid” classification based on insufficient safety data. The Natural Medicines Database classifies melatonin as “Possibly Unsafe” during pregnancy. Melatonin crosses the placenta and plays important roles in fetal development and pregnancy maintenance, but these are regulated by endogenous production rather than supplementation. No well-designed human studies have established safety for supplemental melatonin throughout pregnancy. Major obstetric organizations, including ACOG, do not recommend melatonin supplementation during pregnancy. In some situations the benefits of melatonin supplementation outweigh the risks. When this is the case melatonin should be prescribed and not purchased over the counter to ensure the individual is getting the correct dosage.
For breastfeeding individuals, melatonin receives an “Limited” classification. Natural melatonin levels in breast milk follow circadian rhythms, with higher concentrations at night, helping establish infant sleep-wake cycles. Supplemental melatonin could potentially disrupt these natural patterns. However, adequate sleep is crucial for healing, mental health, and breastmilk production. Talk to your child’s pediatrician before taking melatonin.
Additional considerations include significant variability in commercial melatonin products. Studies by the Journal of Clinical Sleep Medicine have found actual melatonin content in supplements can vary by more than 80% from labeled amounts, and some products contain undeclared serotonin. Melatonin may also interact with various medications including anticoagulants, immunosuppressants, and other hormonal treatments.
Sources: Natural Medicines Database Professional Monograph on Melatonin, Journal of Ovarian Research Studies, Fertility and Sterility Clinical Trials, Journal of Pineal Research Animal Studies, American Society for Reproductive Medicine Resource Documents, Journal of Clinical Sleep Medicine Product Analyses, Academy of Breastfeeding Medicine Protocols