Relationship between melatonin and high-risk pregnancy: A review of investigations published between the years 2010 and 2020

Melatonin in Human Breast Milk and Its Potential Role in Circadian Entrainment: A Nod towards Chrononutrition?

Breastfeeding is the most appropriate source of a newborn's nutrition; among the plethora of its benefits, its modulation of circadian rhythmicity with melatonin as a potential neuroendocrine transducer has gained increasing interest. Transplacental transfer assures melatonin provision for the fetus, who is devoid of melatonin secretion. Even after birth, the neonatal pineal gland is not able to produce melatonin rhythmically for several months (with an even more prolonged deficiency following preterm birth). In this context, human breast milk constitutes the main natural source of melatonin: diurnal dynamic changes, an acrophase early after midnight, and changes in melatonin concentrations according to gestational age and during the different stages of lactation have been reported. Understudied thus far are the factors impacting on (changes in) melatonin content in human breast milk and their clinical significance in chronobiological adherence in the neonate: maternal as well as environmental aspects have to be investigated in more detail to guide nursing mothers in optimal feeding schedules which probably means a synchronized instead of mistimed feeding practice. This review aims to be thought-provoking regarding the critical role of melatonin in chrononutrition during breastfeeding, highlighting its potential in circadian entrainment and therefore optimizing (neuro)developmental outcomes in the neonatal setting.

Sleep deprivation during pregnancy leads to poor fetal outcomes in Sprague-Dawley rats

Sleep deprivation is a common problem during pregnancy, but its impact on the fetus remains unclear. We aimed to investigate the effect of sleep deprivation during pregnancy on fetal outcomes and its mechanism in Sprague-Dawley rats. Sleep deprivation was performed from gestational day(GD) 1-19 using a multiplatform method for 18 h/day. Rats were sacrificed on GD20, and their blood and placentas were collected. Fetal and placental parameters were ascertained. Melatonin, adrenocorticotropic hormone (ACTH) and corticosterone were also measured in serum. The levels of arylalkylamine N-acetyltransferase (AANAT) and two melatonin receptors MT1 and MT2, in placental tissues were detected by western blotting. The inflammatory status and oxidative stress in serum and placentas were investigated. Miscarriage and intrauterine growth restriction were observed in the sleep deprivation group. Sleep deprivation resulted in an increased fetal absorption rate, while fetal weight, crown-rump length and placental weight were reduced. Placental histopathology showed that the labyrinth ratio in the sleep deprivation group was significantly reduced, with hypoplastic villi and obviously decreased blood vessels. Sleep deprivation decreased melatonin in serum and the expression of AANAT, MT1 and MT2 in placental tissues, elevated the oxidative stress products 8-hydroxy-deoxyguanosine (8-OHdG) and malondialdehyde(MDA) in serum and 4-hydroxynonenal (4HNE) in the placenta, and decreased the antioxidants superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) in serum. Serum proinflammatory cytokines including interleukin-1-beta (IL-1β), interleukin-6 (IL-6), necrotizing factor-alpha (TNF-α), and interleukin-8(IL-8), were all elevated by sleep deprivation, and the inflammatory regulatory factor nuclear factor-κB p65 (NF-κB p65) in the placenta was enhanced when examined by immunohistochemistry. Corticosterone levels were comparable between the two groups, although ACTH levels were elevated significantly in the sleep deprivation group. Our study revealed that sleep deprivation during pregnancy can adversely impact fetal outcomes. Melatonin may play an important role in this pathology through the oxido-inflammatory process.

Mental health, sleep quality, and hormonal circadian rhythms in pregnant women with threatened preterm labor: a prospective observational study

BACKGROUND

Threatened preterm labor (TPL) is an important obstetrical challenge. Pregnant women with TPL may develop psychological and physical problems such as mental health disorders, sleep disturbance, and hormonal circadian rhythm disruption. This study aimed to investigate the current state of mental health, sleep quality, and circadian rhythms of cortisol and melatonin secretion in pregnant women with TPL and normal pregnant women (NPW).

METHODS

A prospective observational clinical study was conducted at a maternal and child health hospital in Fuzhou, China, between June and July 2022. A total of 50 women between 32 and 36 weeks of gestation (TPL group, n = 20; NPW group, n = 30) were recruited. Data on anxiety symptom (Zung's Self-rating Anxiety Scale, SAS), depression symptom (Edinburgh Postnatal Depression Scale, EPDS), subjective sleep quality (Pittsburgh Sleep Quality Index, PSQI) and objective sleep outcomes (measured by actigraphy) of the pregnant women were collected at the time of enrolment. Salivary samples were collected once every 6 h (i.e., at 06:00, 12:00, 18:00, and 00:00) during 2 consecutive days to measure the circadian rhythm of hormone (cortisol and melatonin).

RESULTS

There were no differences found in the total scores of SAS, EPDS scores, subjective sleep quality between the TPL and NPW groups (P > 0.05). In contrast, significant differences were found in sleep efficiency, total sleep time, wake time after sleep onset, and average awakening time between the groups (P < 0.05). The circadian rhythm of melatonin secretion was disrupted in the TPL group (P = 0.350); however, it was maintained in the NPW group (P = 0.044). The circadian rhythm of cortisol secretion was disrupted in both groups (P > 0.05).

CONCLUSIONS

In the third trimester of pregnancy, women with TPL suffer from poorer sleep quality and disruption of circadian rhythm of melatonin secretion compared with NPW. Nevertheless, there were no differences found in mental health (i.e., anxiety and depression) and circadian rhythm of cortisol secretion. Large-scale studies should be conducted to evaluate these changes in women with TPL.

TRIAL REGISTRATION

The study was registered from Chinese Clinical Trial Registry (Number: ChiCTR2200060674) on 07/06/2022.

Melatonin-Attenuated Oxidative Stress in High-Risk Pregnant Women Receiving Enoxaparin and Aspirin

Objective

In pregnancy, reducing inflammation and oxidative stress is important. Administration of melatonin during pregnancy can improve reproductive performance by improving the placental antioxidant system and inflammatory response. This investigation was carried out to evaluate the beneficial impact of melatonin on the oxidative stress state among high-risk pregnant women receiving enoxaparin and aspirin.

Methods

In this double-blind, placebo-controlled trial, 40 pregnant women, aged 15-45 years at 6 weeks of pregnancy, were randomly selected and divided into intervention and control groups. The control group received prophylaxis enoxaparin and aspirin once daily between 6 and 16 weeks of pregnancy. The intervention group was taken enoxaparin and aspirin for 9 weeks and melatonin once daily from the sixth week of pregnancy to delivery time. Blood samples were taken to measure some oxidative stress biomarkers including total antioxidant capacity (TAC), malondialdehyde (MDA), total thiol (T-SH), protein carbonyl (PCO), and nitric oxide (NO). The level of high-sensitivity C-reactive protein (hs-CRP) was also determined.

Results

TAC and T-SH levels increased significantly in the intervention group in comparison with the control group. Melatonin administration compared to the control group led to a significantly decreased level of NO and an insignificant hs-CRP level.

Conclusion

Melatonin supplementation in high-risk pregnancy had favorable effects on TAC, T-SH, NO, and hs-CRP levels, improved antioxidant activity, and reduced inflammation. More studies are needed in different pregnancy conditions along with the measurement of different biomarkers.

The Role of Melatonin in Pregnancy and the Health Benefits for the Newborn

In the last few years, there have been significant evolutions in the understanding of the hormone melatonin in terms of its physiology, regulatory role, and potential utility in various domains of clinical medicine. Melatonin's properties include, among others, the regulation of mitochondrial function, anti-inflammatory, anti-oxidative and neuro-protective effects, sleep promotion and immune enhancement. As it is also bioavailable and has little or no toxicity, it has been proposed as safe and effective for the treatment of numerous diseases and to preserve human health. In this manuscript, we tried to evaluate the role of melatonin at the beginning of human life, in pregnancy, in the fetus and in newborns through newly published literature studies.

A randomized controlled trial on the effect of blue-blocking glasses compared to partial blue-blockers on melatonin profile among nulliparous women in third trimester of the pregnancy

OBJECTIVE

In pregnancy melatonin regulates circadian rhythms, induce sleep, and has a neuroprotective positive effect on fetal development. Artificial blue light in the evening delays and suppresses melatonin production. Thus, we investigated the effect of blocking blue light on the melatonin profile.

METHODS

A randomized controlled trial (n=30 blue-blocking glasses vs. n=30 control glasses with partial blue-blocking effect) including healthy nulliparous pregnant women in the beginning of the third trimester. Salivary melatonin and subjective sleep were measured before and after two weeks of intervention/control condition. Saliva was sampled at 30-min intervals from 3 h before normal bedtime. Melatonin onset was set at 4.0 pg/ml.

RESULTS

Due to missing data melatonin onset was estimated for 47 participants. At posttreatment, melatonin onset advanced by 28 min in the blue-blocking group compared with the control condition (p=.019). Melatonin levels were significantly higher, favoring the blue-blocking glass condition, at clock time 20:00, 21:00 and 22:00 h, and for sample number 3 and 4. The phase angle (time interval) between melatonin onset and sleep bedtime and sleep onset time increased within the blue blocking group (+45 min and +41 min, respectively), but did not reach statistical significance compared to control condition (+13 min and +26 min, respectively).

CONCLUSION

Blocking blue light in the evening had a positive effect on the circadian system with an earlier onset and rise of melatonin levels in healthy nulliparous pregnant women. This demonstrated the effectiveness and feasibility of a simple non-pharmacological chronobiological intervention during pregnancy.