Is melatonin safe to use during pregnancy?

Safety of Melatonin During Pregnancy

Melatonin should be used with caution during pregnancy due to insufficient safety data in humans, although current evidence suggests it is likely not harmful.

Current Evidence on Melatonin in Pregnancy

The safety of melatonin during pregnancy has not been thoroughly evaluated in large-scale human clinical trials. While there is no specific FDA classification for melatonin in pregnancy, the approach to its use should follow principles similar to those applied to other medications during pregnancy.

What We Know About Melatonin in Pregnancy:

• Melatonin is a naturally occurring hormone that crosses the placenta freely 1
• Maternal melatonin levels naturally increase progressively during pregnancy 2
• Melatonin provides photoperiodic information to the fetus and plays a role in fetal brain development 2
• Recent scoping reviews suggest that, contrary to concerns raised in animal studies, melatonin use during human pregnancy has not demonstrated major safety concerns in the limited clinical studies available 3

Potential Benefits vs. Risks

Potential Benefits:

• Acts as an antioxidant that may protect against oxidative stress in the placenta 4
• May play a protective role in fetal brain development 2
• Could potentially help with sleep disorders, which are common during pregnancy 3

Potential Risks:

• Limited human safety data from controlled trials
• Most safety data comes from small studies or case reports rather than large randomized controlled trials
• Long-term effects on offspring development are not well established

Decision-Making Algorithm for Melatonin Use in Pregnancy

1. First-line approach: Non-pharmacological sleep interventions

   • Sleep hygiene practices
   • Cognitive behavioral therapy for insomnia
   • Regular physical activity (as appropriate for pregnancy)
   • Avoidance of caffeine and electronic devices before bedtime

2. If sleep problems persist:

   • Assess severity of sleep disturbance and impact on maternal health
   • Consider risks vs. benefits of melatonin compared to untreated sleep problems
   • Discuss with patient that melatonin lacks comprehensive safety data in pregnancy

3. If melatonin is considered:

   • Use the lowest effective dose
   • Use for shortest duration necessary
   • Preferably avoid during first trimester when organogenesis occurs
   • Monitor for any adverse effects

Important Considerations and Caveats

• The prevalence of melatonin use during pregnancy is estimated at around 4% according to health administrative database surveys 3
• Unlike prescription medications, melatonin is a dietary supplement not regulated by the FDA for efficacy, safety, or quality
• Dosage and purity of over-the-counter melatonin products can vary significantly
• There are no established guidelines specifically addressing melatonin use in pregnancy

Conclusion for Clinical Practice

While emerging research suggests melatonin may have protective effects during pregnancy 4, 5, the lack of robust human clinical trials and formal safety categorization necessitates caution. Until more definitive evidence is available, non-pharmacological approaches to sleep problems should be prioritized during pregnancy, with melatonin reserved for cases where the potential benefits may outweigh the theoretical risks.