This sheet is about exposure to melatonin in pregnancy and while breastfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.

What is melatonin?

Melatonin is a hormone made by the body that helps with the natural sleep-wake cycle (called circadian rhythm). Melatonin is made by the body mostly during periods of darkness in the night. During pregnancy, the body typically makes more melatonin. Studies suggest that melatonin levels are highest in the third trimester of pregnancy and levels are expected to return to normal after delivery.

Melatonin is also available as a supplement sold over the counter. Taking melatonin supplements during pregnancy has not been well studied. In general, it is suggested to speak with your healthcare provider before taking any supplements. Many supplements are not recommended for use during pregnancy unless your healthcare provider has prescribed them to treat a medical condition. This is because they are not well-regulated nor studied for use in pregnancy. For more detail on supplements, please see the fact sheet at https://mothertobaby.org/fact-sheets/herbal-products-pregnancy/.

I take melatonin. Can it make it harder for me to get pregnant?

A small number of limited studies that have looked at use of melatonin among people with infertility who were undergoing in vitro-fertilization (IVF) treatments have not shown an increase in pregnancy rates.

Does taking melatonin increase the chance of miscarriage?

This has not been well studied. Miscarriage is common and can occur in any pregnancy for many different reasons. Studies that have looked at melatonin use for infertility have not shown any increases in the chance of miscarriage.

Does taking melatonin increase the chance of birth defects?

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. It is not known if taking melatonin would increase the chance of birth defects. The few studies that have been done in humans with the use of melatonin for the treatments of some conditions in pregnancy (to reduce blood loss during C-section and improve success of in vitro fertilization) have not suggested an increased chance of birth defects.

Does taking melatonin in pregnancy increase the chance of other pregnancy-related problems?

Studies have not been done to see if taking melatonin supplements can increase the chance of other pregnancy-related problems, such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). Studies exploring the use of melatonin to reduce blood loss during C-section deliveries found mixed results with 3 studies showing less blood loss and 1 study showing no difference in blood loss.

Does taking melatonin in pregnancy affect future behavior or learning for the child?

Studies have not been done to see if taking melatonin supplements can cause behavior or learning issues for the child.

Breastfeeding while taking melatonin:

Melatonin made by the body is present in breastmilk in higher amounts at night. Taking melatonin supplements while breastfeeding has not been well studied. One case has been reported of an infant with a bleeding problem while being breastfed by an individual who was taking a supplement that had melatonin and valerian. This bleeding problem has not been reported in other studies, including studies where melatonin was given directly to infants. Be sure to talk to your healthcare provider about all your breastfeeding questions.

If a male takes melatonin, could it affect fertility or increase the chance of birth defects?

Based on the studies reviewed, it is not known if melatonin supplements could affect male fertility (ability to get partner pregnant) or increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.

Selected References:

• Albzea W, et al. 2023. Efficacy and safety of preoperative melatonin for women undergoing cesarean section: a systematic review and meta-analysis of randomized placebo-controlled trials. Medicina (Kaunas), 59(6):1065. [PMC free article: PMC10302920] [PubMed: 37374268]
• Alkhfaji H, et al. 2023. Impact of melatonin as a premedication agent in caesarean section on blood loss and postoperative pain level. Anesthesiol Res Pract, 2023:8102111. [PMC free article: PMC10730253] [PubMed: 38116042]
• Amaral FGD and José C. 2018. A brief review about melatonin, a pineal hormone. Archives of Endocrinology and Metabolism, 62(4):472-479. [PMC free article: PMC10118741] [PubMed: 30304113]
• Andersen LP, et al. 2016. The safety of melatonin in humans. Clin Drug Investig, 36:169–175. [PubMed: 26692007]
• Davis, F. C. (1997). Melatonin: role in development. Journal of Biological Rhythms, 12(6):498–508. [PubMed: 9406023]
• Díaz E, et al. 2000. Effect of prenatal melatonin on the gonadotropin and prolactin response to the feedback effect of testosterone in male offspring. The Journal of Steroid Biochemistry and Molecular Biology, 72(1):61-69. [PubMed: 10731639]
• Díaz, E, et al. 1999. Prenatal melatonin exposure influences the maturation of gonadotropin and prolactin estradiol-benzoate feedback system. The Journal of Steroid Biochemistry and Molecular Biology, 70(1): 81-88. [PubMed: 10529005]
• Ejaz F, et al. 2020. Maternal serum melatonin increases during pregnancy and falls immediately after delivery implicating the placenta as a major source of melatonin. Frontiers in Endocrinology (Lausanne), 11:623038–623038. [PMC free article: PMC7930478] [PubMed: 33679607]
• Garofoli F, et al. 2023. Fate of melatonin orally administered in preterm newborns: antioxidant performance and basis for neuroprotection. J Pineal Res, 76(1):e12932. [PubMed: 38111174]
• Garofoli F, et al. 2021. Oral melatonin as a new tool for neuroprotection in preterm newborns: study protocol for a randomized controlled trial. Trials, 22(1):82. [PMC free article: PMC7820522] [PubMed: 33482894]
• Gowda SK. 2022. A comparative study to evaluate the effect of melatonin on blood loss after elective Caesarean section: a randomized double blind study. Indian J Anaesth, 66(Suppl 1):S17-S18.
• Grivas T, et al. 2007. Melatonin the “light of the night” in human biology and adolescent idiopathic scoliosis. Scoliosis, 2,6. [PMC free article: PMC1855314] [PubMed: 17408483]
• Hardeland R. 2009. New approaches in the management of insomnia: weighing the advantages of prolonged-release melatonin and synthetic melatoninergic agonists. Neuropsychiatric Disease and Treatment, 5:341–354. [PMC free article: PMC2699659] [PubMed: 19557144]
• Harpsøe NG, et al. 2015. Clinical pharmacokinetics of melatonin: a systematic review. Eur J Clin Pharmacol, 71:901–909. [PubMed: 26008214]
• Iavarone S, et al. 2023. Antiplatelet effect of melatonin through breastfeeding: a pediatric case report. Children (Basel), 10(12):1839. [PMC free article: PMC10741506] [PubMed: 38136041]
• Jayashree, et al. 2021. Effect of melatonin in reducing blood loss during and after caesarean section. Int J Clin Obstet Gynecol, 5(6):227-231.
• Katzer D, et al. 2016. Melatonin concentrations and antioxidative capacity of human breast milk according to gestational age and the time of day. J Hum Lact, 32:NP105–NP110. [PubMed: 27121237]
• Khezri MB, et al. 2019. Effect of melatonin on blood loss after cesarean section: a prospective randomized double-blind trial. J Obstet Gynaecol India, 69(5):436-443. [PMC free article: PMC6765044] [PubMed: 31598047]
• Luboshitzky R, et al. 2002. Melatonin administration alters semen quality in healthy men. J Androl, 4:572-578. [PubMed: 12065466]
• Mannino G, et al. 2021. Melatonin and phytomelatonin: chemistry, biosynthesis, metabolism, distribution and bioactivity in plants and animals-an overview. International Journal of Molecular Sciences, 22(18):9996. [PMC free article: PMC8469784] [PubMed: 34576159]
• Mejlhede MAB, et al. 2021. Oral melatonin supplementation during in vitro fertilization treatment: a systematic PRISMA review and meta-analysis of randomized controlled trials. Gynecological Endocrinology, 37(12):1079-1085. [PubMed: 34494508]
• Moradi M, et al. 2021. Melatonin protects rats testes against bleomycin, etoposide, and cisplatin-induced toxicity via mitigating nitro-oxidative stress and apoptosis. Biomed Pharmacother, 138:111481. [PubMed: 33752059]
• Okatani Y, et al.2001. Effect of prenatal melatonin exposure on gonadotropins and prolactin secretion in male and female rat pups. European Journal of Pharmacology, 424(3):229-235. [PubMed: 11672567]
• Ramiro-Cortijo D, et al. 2020. Maternal antioxidant status in early pregnancy and development of fetal complications in twin pregnancies: a pilot study. Antioxidants, 9(4):269 [PMC free article: PMC7222178] [PubMed: 32218124]
• Showell MG, et al. 2020. Antioxidants for female subfertility. Cochrane Database Syst Rev, 8(8):CD007807. [PMC free article: PMC8094745] [PubMed: 32851663]
• Sun TC, et al. 2020. Protective effects of melatonin on male fertility preservation and reproductive system. Cryobiology, 95:1-8 [PubMed: 32001217]
• Vine T, et al. 2022. Melatonin use during pregnancy and lactation: a scoping review of human studies. Braz J Psychiatry, 44(3):342-348. [PMC free article: PMC9169489] [PubMed: 34730672]
• Yang HL, et al. 2018. Pleiotropic roles of melatonin in endometriosis, recurrent spontaneous abortion, and polycystic ovary syndrome. Am J Reprod Immunol, 80(1):e12839. [PubMed: 29493042]