Serum and amniotic fluid melatonin during human labor

Area of Science:

• Reproductive Endocrinology
• Chronobiology
• Maternal-Fetal Medicine

Background:

• Melatonin (MT) is a hormone with known circadian and physiological roles.
• Understanding melatonin's role during human pregnancy and labor is crucial for maternal and fetal well-being.
• Previous research has not fully elucidated the diurnal patterns and labor-related influences on maternal and amniotic fluid melatonin.

Purpose of the Study:

• To investigate the serum and amniotic fluid concentrations of melatonin (MT) during human labor.
• To determine if labor progression, delivery type, or time of day influences MT levels.
• To assess the relationship between serum and amniotic fluid MT concentrations during delivery.

Main Methods:

• Serum and amniotic fluid samples were collected from women during labor.
• Melatonin concentrations were measured using radioimmunoassay (RIA).
• High-pressure liquid chromatography (HPLC) was used to confirm MT identity in amniotic fluid.

Main Results:

• Serum MT concentrations exhibited a significant diurnal rhythm, higher at night than during the day.
• Amniotic fluid MT concentrations also showed a diurnal pattern, correlating positively with serum MT.
• Neither labor progress, induction methods (amniotomy, oxytocin), nor operative delivery (cesarean section) affected serum MT levels.

Conclusions:

• Human melatonin secretion during labor is primarily regulated by the time of day, not physical stress or endocrine changes of parturition.
• The diurnal rhythm of melatonin is maintained in serum and amniotic fluid during human labor.
• Melatonin levels in amniotic fluid are lower than in maternal serum during the night.