8331 Melatonin is associated with higher placental weight and higher birth weight

Abstract Disclosure: U. Kampmann: Grant Recipient; Self; Novo Nordisk, Ulla Kampmann. Speaker; Self; Merck, Novo Nordisk. E.S. Lauritzen: None. S. Knorr: None. M. Bjerre: None. L.J. Goodyear: None. R. Middelbeek: None. J. Kusuyama: None. J. Fuglsang: None. P. Ovesen: Grant Recipient; Self; Novo Nordisk. M. Møller: None. Background and aim: Melatonin is both a neuroendocrine hormone which regulates circadian rhythm and an antioxidant. Melatonin is primarily produced in the pineal gland but also in the placenta and the role of melatonin in pregnancy is emerging. We examined melatonin levels during pregnancy and performed correlations with placental weight, birth weight and birth weight Z-score as markers of placental function. Material and methods: Blood samples were obtained in each trimester of pregnancy from a cohort of 400 pregnant women, followed at a Danish University Hospital. Data on pre-gestational BMI, smoking status, placental weight, birth weight and Z-score were collected. Melatonin, and biomarkers of oxidative stress: SOD3, CD 163 and CRP were measured on blood samples collected in the morning. Correlations were calculated using mixed models. Results: We included 372 healthy, singleton pregnancies. Melatonin levels increased significantly throughout pregnancy from 17.0 pg/mL (95% CI: 14.1 - 19.9) and 18.8 pg/mL (95% CI: 15.8 - 21.8) in the 1st and 2nd trimester, respectively, to 45.9 pg/mL (95% CI: 40.8 - 51.0) in the 3rd trimester. There was a significant positive correlation between the antioxidant enzyme SOD3 and melatonin throughout pregnancy with a coefficient of 0.15 (95% CI: 0.13 - 0.17) and there was a significant positive association between placental weight and melatonin (coefficient: 0.014 (95% CI: 0.000 - 0.028)) and Z-score and melatonin levels (coefficient: 1.95 (95% CI: 0.13 - 3.79)). This was however not significant when adjusting for smoking and pre-pregnancy BMI. Conclusion: The current study is to date, the largest study that have performed longitudinal measures of melatonin throughout pregnancy. Melatonin levels increase significantly during pregnancy and indicate that placenta is a major source of melatonin, that plays a protective role against oxidative stress in pregnancy. Presentation: 6/1/2024