Changes of serum melatonin level and its relationship to feto‐placental unit during pregnancy

Abstract

Serum melatonin concentrations were studied in normal pregnant women and in women with several types of pathologic pregnancies, e.g., twins, preeclampsia or intrauterine growth retardation (IUGR). Blood samples were collected from the maternal antecubital vein at 14:00 hr (daytime) and 02:00 hr (nighttime) during pregnancy, and also from the umbilical vein and artery immediately after delivery. Serum melatonin concentrations were measured by radioimmunoassay. Daytime serum melatonin levels in normal (single fetus; singleton) pregnancies were low. While the levels showed an increasing tendency toward the end of pregnancy, no statistically significant changes occurred. On the other hand, the nighttime serum melatonin levels increased after 24 weeks of gestation, with significantly (P < 0.01) high levels after 32 weeks; these values decreased to non-pregnant levels on the 2nd day of puerperium. Nighttime serum melatonin levels were significantly (P < 0.05) higher in twin pregnancies after 28 weeks of gestation than in singleton pregnancies, whereas the patients with severe preeclampsia showed significantly (P < 0.05) lower serum melatonin levels than the mild preeclampsia or the normal pregnant women after 32 weeks of gestation. Melatonin concentrations in umbilical vessels showed a higher tendency in neonates who were born during at night compared with the other neonates; moreover, those in the umbilical artery were generally higher than those in the umbilical vein. The present results indicate that in humans, the maternal serum melatonin levels show a diurnal rhythm, which increases until the end of pregnancy, reflecting some pathologic states of the feto-placental unit. Fetuses may produce melatonin with a circadian rhythm.

Effects of Night Work on Urinary Excretion Rates of 6-Sulfatoxymelatonin, Norepinephrine and Estriol in Pregnant Women.

“…Although there was no statistical significance, the aMT6s levels of the pregnant subjects were apt to be higher than those of the non-pregnant. The same tendency was reported in other articles 25,26) . However, the association of melatonin secretion with reproductive function such as pregnancy remains unestablished 19) .…”

“…The change in melatonin level with advancing gestational age is also controversial. Some researchers have reported that melatonin levels might be altered during gestation 26,27) , while others reported unaltered 9,28) . As for this study on urinary metabolites, aMT6s, it displayed no significant alterations from the G1 when the subjects were on work to the G4 when out of work.…”

The Relationship of Nocturnal Melatonin to Estradiol and Progesterone in Depressed and Healthy Pregnant Women

“…Our current findings confirm and extend our earlier report 8 showing that nocturnal melatonin AUC increased across weeks of pregnancy in HW but not in DW. Nakamura et al 27 also found that serum melatonin level increased as gestation progressed in normal pregnant women. Thus, E 2 and P 4 may be part of an important mechanism associated with increased melatonin quantity during pregnancy in HW.…”

The effects of extremely low frequency magnetic fields on mutation induction in mice

“…This suggestion is of note following the proposed general model pertaining to the onset and progression of childhood leukaemia which assumes that any initial event(s) occurs in utero (Greaves, 1999) (Chapter 1.2). While the same is potentially true in pregnant women where Nakamura et al (2001) illustrated that serum melatonin possesses a diurnal rhythm which rises substantially following 24 weeks gestation and remains elevated until the full term. Indeed the addition of radical scavengers and antioxidants were able to inhibit an ELF-MF related increase in cell proliferation (Wolf et al, 2005), the MFinduced production of superoxide radical anions (Mannerling et al, 2010) and also prevent the previously observed induction of single-and double-strand breaks in brain cells of rats following ELF-MF exposure .…”