Melatonin concentration in umbilical cord blood depends on mode of delivery

Physical environment of the operating room during cesarean section: A systematic review

INTRODUCTION

Environmental factors in the operating room during cesarean sections are likely important for both women/birthing people and their babies but there is currently a lack of rigorous literature about their evaluation. The principal aim of this study was to systematically examine studies published on the physical environment in the obstetrical operating room during c-sections and its impact on mother and neonate outcomes. The secondary objective was to identify the sensors used to investigate the operating room environment during cesarean sections.

METHODS

In this literature review, we searched MEDLINE a database using the following keywords: Cesarean section AND (operating room environment OR Noise OR Music OR Video recording OR Light level OR Gentle OR Temperature OR Motion Data). Eligible studies had to be published in English or French within the past 10 years and had to investigate the operating room environment during cesarean sections in women. For each study we reported which aspects of the physical environment were investigated in the OR (i.e., noise, music, movement, light or temperature) and the involved sensors.

RESULTS

Of a total of 105 studies screened, we selected 8 articles from title and abstract in PubMed. This small number shows that the field is poorly investigated. The most evaluated environment factors to date are operating room noise and temperature, and the presence of music. Few studies used advanced sensors in the operating room to evaluate environmental factors in a more nuanced and complete way. Two studies concern the sound level, four concern music, one concerns temperature and one analyzed the number of entrances/exits into the OR. No study analyzed light level or more fine-grained movement data.

CONCLUSIONS

Main findings include increase of noise and motion at specific time-points, for example during delivery or anaesthesia; the positive impact of music on parents and staff alike; and that a warmer theatre is better for babies but more uncomfortable for surgeons.

The fetal gastrointestinal tract is exposed to melatonin and superoxide dismutase rich amniotic fluid throughout prenatal development

Amniotic fluid (AF) is the first fluid to enter the gastrointestinal tract. Preterm birth is leading to a sudden interruption of AF swallowing. Understanding the composition of amniotic fluid is crucial to implement strategies preventing intestinal injury in preterm infants. We hypothesized that the fetal gastrointestinal tract (GIT) is exposed to melatonin and antioxidant enzymes via amniotic fluid throughout prenatal development. Amniotic fluid samples from 76 pregnant women with a median (range) gestational age of 38.0 (14.3–40.1) weeks have been collected. Immediately after birth blood samples were collected from the umbilical vein (n = 53). Median (Interquartile range) melatonin concentration was 30.5 pg/ml (12.7–118.3) and superoxide dismutase 1 (SOD1) concentration was 84 ng/ml (59–123). Extracellular glutathione peroxidase concentration was either not detectable or exceptionally low. We found a positive correlation between melatonin concentration in amniotic fluid and gestational age (Spearman’s correlation coefficient, r = 0.570, p<0.001), while SOD1 concentration in amniotic fluid was inversely correlated with gestational age (r = −0.246, p = 0.032). Compared to serum samples, melatonin concentration was statistically significantly higher in amniotic fluid (p<0.001). Our results indicate that the fetal gastrointestinal system is continuously exposed to melatonin and SOD1 via the amniotic fluid throughout prenatal development.

Three kinds of caesarean sections: the foetal/neonatal perspective

In the age of hospital births, it is commonplace to contrast the vaginal route and the abdominal route as the basic classification. From the "point of view" of the foetus/neonate, we provide reasons to contrast "birth without labour" (that is birth by pre-labour caesarean section) and all the other vaginal and abdominal modes of birth. From a great diversity of theoretical reasons, one can anticipate that babies born by pre-labour caesarean sections are different from the others. We also provide reasons to popularize the concepts of "in labour non-emergency caesarean sections" and "planned in-labour caesarean sections".

Effects of altered photoperiod due to COVID-19 lockdown on pregnant women and their fetuses

Maternal circadian rhythms provide highly important input into the entrainment and programming of fetal and newborn circadian rhythms. The light-dark cycle is an important regulator of the internal biological clock. Even though pregnant women spend a greater part of the day at home during the latter stages of pregnancy, natural light exposure is crucial for the fetus. The current recommended COVID-19 lockdown might dramatically alter normal environmental lighting conditions of pregnant women, resulting in exposure to extremely low levels of natural daylight and high-intensity artificial light sources during both day and night. This article summarizes the potential effects on pregnant woman and their fetuses due to prolonged exposure to altered photoperiod and as consequence altered circadian system, known as chronodisruption, that may result from the COVID-19 lockdown.

Maternal Serum Melatonin Increases During Pregnancy and Falls Immediately After Delivery Implicating the Placenta as a Major Source of Melatonin

Melatonin is a neuroendocrine hormone which regulates circadian rhythm and is also an antioxidant. The role of melatonin in pregnancy is emerging. The enzymes needed for endogenous synthesis of melatonin have been identified in the placenta, although the contribution to circulating maternal melatonin in normal pregnancy is unclear. This work aimed to determine serum levels of melatonin and its major metabolite 6-hydroxymelatonin sulfate (6-OHMS) in normal pregnant women during each trimester of pregnancy, and immediately after delivery. Blood samples were obtained from a cohort of healthy pregnant women during each trimester of pregnancy (n = 26), from women scheduled for elective Cesarean section (CS) before and after delivery (n = 15), along with placental samples, and from healthy non-pregnant women as controls (n = 30). Melatonin and its major metabolite, 6-OHMS, were measured using enzyme immunoassay. Levels of serum melatonin were significantly higher during pregnancy than in non-pregnant women (P = 0.025) and increased throughout pregnancy (P < 0.0001). In women undergoing CS, serum melatonin decreased markedly 24 h after delivery (P = 0.0013). Similar results were seen for serum levels of 6-OHMS, and placental tissue 6-OHMS levels correlated with week of gestation at delivery (p = 0.018). In summary, maternal melatonin production is higher in pregnant than in non-pregnant women, increases significantly during pregnancy with highest levels in the third trimester, and decreases abruptly after delivery. These results suggest that the placenta is a major source of melatonin and supports a physiological role for melatonin in pregnancy.

Melatonin in Hypoxic-Ischemic Brain Injury in Term and Preterm Babies

Melatonin may serve as a potential therapeutic free radical scavenger and broad-spectrum antioxidant. It shows neuroprotective properties against hypoxic-ischemic brain injury in animal models. The authors review the studies focusing on the neuroprotective potential of melatonin and its possibility of treatment after perinatal asphyxia. Melatonin efficacy, low toxicity, and ability to readily cross through the blood-brain barrier make it a promising molecule. A very interesting thing is the difference between the half-life of melatonin in preterm neonates (15 hours) and adults (45-60 minutes). Probably, the use of synergic strategies-hypothermia coupled with melatonin treatment-may be promising in improving antioxidant action. The authors discuss and try to summarize the evidence surrounding the use of melatonin in hypoxic-ischemic events in term and preterm babies.

Antioxidative status and oxidative stress in the fetal circulation at birth: the effects of time of delivery and presence of labor

BACKGROUND

There are important physiological changes in the maternal, placental, and fetal compartments during pregnancy and labor. Increased oxidative stress has been demonstrated during labor. Melatonin has been reported to serve as an indirect antioxidant via the stimulation and induction of antioxidant enzymes as superoxide dismutase (SOD) and glutathione peroxidase (Gpx) in several tissues.

AIM

: To assess whether the melatonin status, presence of labor at the time of birth and the time of delivery influence the extracellular antioxidative enzymes and DNA oxidative stress in newborns.

METHODS

The extracellular antioxidative status and oxidative stress were analyzed by measuring the concentrations of the SOD3, Gpx3 and 8-hydroxydeoxyguanosine (8-OHdG) in the cord blood of 135 newborns. Newborns delivered during the day and at night and newborns delivered by spontaneous vaginal delivery (labor group) or elective caesarean section delivery (no labor group) were studied.

OUTCOME MEASURES

The concentration of melatonin, SOD3, Gpx3 and 8-OHdG.

RESULTS

Independent of the time of delivery, we found significantly higher melatonin, SOD3 and Gpx3 but lower 8-OHdG concentrations in the labor group than in the no labor group. We did not observe a correlation between the concentration of melatonin and SOD3, Gpx3 or 8-OHdG, or a day-night difference in SOD3, Gpx3 or 8-OHdG.

CONCLUSION

Our findings suggest that oxidative stress during labor leads to an elevation of melatonin, SOD3 and Gpx3 in the fetal circulation, protecting the newborn from serious impairment, which is reflected by lower 8-OHdG levels. The melatonin status at the time of birth does not influence the extracellular SOD3 or Gpx3 concentrations.

Is melatonin ready to be used in preterm infants as a neuroprotectant?

The prevention of neurological disabilities following preterm birth remains a major public health challenge and efforts are still needed to test the neuroprotective properties of candidate molecules. Melatonin serves as a neuroprotectant in adult models of cerebral ischemia through its potent antioxidant and anti-inflammatory effects. An increasing number of preclinical studies have consistently demonstrated that melatonin protects the damaged developing brain by preventing abnormal myelination and an inflammatory glial reaction, a major cause of white matter injury. The main questions asked in this review are whether preclinical data on the neuroprotective properties of melatonin are sufficient to translate this concept into the clinical setting, and whether melatonin can reduce white matter damage in preterm infants. This review provides support for our view that melatonin is now ready to be tested in human preterm neonates, and discusses ongoing and planned clinical trials.