Melatonin Levels Decrease in the Umbilical Cord in Case of Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is a common reason for perinatal morbidity and mortality. Also, it is often complicated with fetal distress. Melatonin is widely known as an anti-oxidant agent, and it might decrease the damage of tissues caused by hypoxia. It is also known that levels of pro- and anti-inflammatory cytokines are changed during pregnancy. Placental growth factor (PlGF) is responsible for the angiogenesis in the placenta. We aimed to investigate whether the level of melatonin, cytokines, and PlGF in umbilical blood after birth is different in the case of IUGR compared to normal fetuses. Fourteen women whose pregnancies were complicated with IUGR were included in the study group. The presence of IUGR was confirmed by ultrasound fetometry in the third pregnancy trimester, 30-36 weeks of gestation. All patients delivered their children vaginally after 37 weeks of pregnancy. The cases of severe fetal distress that required a caesarian section, obstetrical forceps, or vacuum extraction of the fetus were excluded from the study. We found that the concentrations of cytokines did not differ significantly between the groups. Also, no significant difference in the daytime of delivery was found between the groups. The concentrations of melatonin and PlGF in the umbilical blood at labor were significantly lowered in the case of IUGR compared to normal pregnancies. This fact, as we consider, is caused by altered production of melatonin and PlGF by the placenta. Therefore, the protective action of these two factors for the fetus at labor is decreased in IUGR.