Behavioral and cortisol responses to stress in newborn infants: Effects of mode of delivery

Changes in DNA methylation associated with a specific mode of delivery: a pilot study

Background

The mode of delivery represents an epigenetic factor with potential to affect further development of the individual by multiple mechanisms. DNA methylation may be one of them, representing a major epigenetic mechanism involving direct chemical modification of the individual's DNA. This pilot study aims to examine whether a specific mode of delivery induces changes of DNA methylation by comparing the umbilical cord blood and peripheral blood of the newborns.

Methods

Blood samples from infants born by vaginal delivery and caesarean section were analysed to prepare the Methylseq library according to NEBNext enzymatic Methyl-seq Methylation Library Preparation Kit with further generation of target-enriched DNA libraries using the Twist Human Methylome Panel. DNA methylation status was determined using Illumina next-generation sequencing (NGS).

Results

We identified 168 differentially methylated regions in umbilical cord blood samples and 157 regions in peripheral blood samples. These were associated with 59 common biological, metabolic and signalling pathways for umbilical cord and peripheral blood samples.

Conclusion

Caesarean section is likely to represent an important epigenetic factor with the potential to induce changes in the genome that could play an important role in development of a broad spectrum of disorders. Our results could contribute to the elucidation of how epigenetic factors, such as a specific mode of delivery, could have adverse impact on health of an individual later in their life.

Activation of Lymphocytes in Healthy Neonates Within Hours of Birth

It is now established that immune maturation occurs along a defined trajectory in the weeks and months after birth, but the immediate changes that occur within immune cells following birth is less clear. In this study, we monitored the immune profile of neonates via analysis of paired samples (n= 28) of cord blood and heel prick blood taken at varying times post term delivery by planned elective caesarean section. This paired approach accounted for the between-subject variability often observed over the first week of life. We identified rapid changes in immune cell populations within hours of birth. Specifically, we observed increased proliferation in effector T cells (but not regulatory T cells) that exhibited an increase in cytokine producing ability and also an increase in the percentage of CD3 T cells over this short time frame. This indicates that the mobilisation of the immune system is immediate post birth, presumably as a response to sudden exposure to the external environment, antigen or stress. Hence, immune development may start to occur more rapidly than previously proposed and as such, to study this trajectory, blood sampling should begin as soon after birth as possible.

Oral Microbiome: Getting to Know and Befriend Neighbors, a Biological Approach

The oral microbiome, forming a biofilm that covers the oral structures, contains a high number of microorganisms. Biofilm formation starts from the salivary pellicle that allows bacterial adhesion-colonization-proliferation, co-aggregation and biofilm maturation in a complex microbial community. There is a constant bidirectional crosstalk between human host and its oral microbiome. The paper presents the fundamentals regarding the oral microbiome and its relationship to modulator factors, oral and systemic health. The modern studies of oral microorganisms and relationships with the host benefits are based on genomics, transcriptomics, proteomics and metabolomics. Pharmaceuticals such as antimicrobials, prebiotics, probiotics, surface active or abrasive agents and plant-derived ingredients may influence the oral microbiome. Many studies found associations between oral dysbiosis and systemic disorders, including autoimmune diseases, cardiovascular, diabetes, cancers and neurodegenerative disorders. We outline the general and individual factors influencing the host-microbial balance and the possibility to use the analysis of the oral microbiome in prevention, diagnosis and treatment in personalized medicine. Future therapies should take in account the restoration of the normal symbiotic relation with the oral microbiome.

Animal Models for Assessing Impact of C-Section Delivery on Biological Systems

There has been a significant increase in Caesarean section (C-section) births worldwide over the past two decades and although it is can be a life-saving procedure, the enduring effects on host physiology are now undergoing further scrutiny. Indeed, epidemiological data have linked C-section birth with multiple immune, metabolic and neuropsychiatric diseases. Birth by C-section is known to alter the colonisation of the neonatal gut microbiota (with C-section delivered infants lacking vaginal microbiota associated with passing along the birth canal), which in turn can impact the development and maintenance of many important biological systems. Appropriate animal models are key to disentangling the role of missing microbes in brain health and disease in C-section births. In this review of preclinical studies, we interrogate the effects of C-section birth on the development (and maintenance) of several biological systems and we discuss the involvement of the gut microbiome on C-section-related alterations.

Parity moderates the effect of delivery mode on maternal ratings of infant temperament

Objective

Cesarean section (CS) rates are rising rapidly around the world but no conclusive evidence has been obtained about the possible short- and long-term effects of CS on child behavior. We evaluated prospectively the association between CS and infant temperament across the first 9 postpartum months, controlling for indications for CS and investigating parity and infant sex as moderators.

Methods

The sample consisted of mothers and their healthy infants. Infant temperament was measured using the Infant Characteristics Questionnaire completed by the mothers at 6 weeks (n = 452) and 9 months (n = 258) postpartum. Mode of birth was classified into spontaneous vaginal birth (n = 347 for 6 weeks sample; 197 for 9 months sample), CS planned for medical reasons (n = 55; 28) and emergency CS (n = 50; 33).

Results

Multiple regression analysis revealed no main effects of birth mode, but showed a significant interaction between birth mode and parity indicating that emergency CS in firstborn infants was associated with more difficult temperament at 6 weeks. There were no significant associations between indications for CS and infant temperament, although breech presentation predicted difficult temperament at 9 months.

Conclusion

We largely failed to support the association between CS and infant temperament. Although our results suggest that emergency CS may be associated with temperament in firstborns, further research is needed to replicate this finding, preferably using observational measures to assess child temperament.

Birth signalling hormones and the developmental consequences of caesarean delivery

Rates of delivery by caesarean section (CS) are increasing around the globe and, although several epidemiological associations have already been observed between CS and health outcomes in later life, more are sure to be discovered as this practice continues to gain popularity. The components of vaginal delivery that protect offspring from the negative consequences of CS delivery in later life are currently unknown, although much attention to date has focused on differences in microbial colonisation. Here, we present the case that differing hormonal experiences at birth may also contribute to the neurodevelopmental consequences of CS delivery. Levels of each of the 'birth signalling hormones' (oxytocin, arginine vasopressin, epinephrine, norepinephrine and the glucocorticoids) are lower following CS compared to vaginal delivery, and there is substantial evidence for each that manipulations in early life results in long-term neurodevelopmental consequences. We draw from the research traditions of neuroendocrinology and developmental psychobiology to suggest that the perinatal period is a sensitive period, during which hormones achieve organisational effects. Furthermore, there is much to be learned from research on developmental programming by early-life stress that may inform research on CS, as a result of shared neuroendocrine mechanisms at work. We compare and contrast the effects of early-life stress with those of CS delivery and propose new avenues of research based on the links between the two bodies of literature. The research conducted to date suggests that the differences in hormone signalling seen in CS neonates may produce long-term neurodevelopmental consequences.

Perinatal cortisol and blood glucose concentrations in bitches and neonatal puppies: effects of mode of whelping

The decision on how and when to assist whelping is crucial for the survival rate of puppies and health status of the dam. However, medical or surgical therapy in dystocia can impact both maternal and neonatal stress and glucose response differently. This study aims to compare perinatal cortisol and glucose among different modes of delivery in bitches and neonates. We analyzed 50 puppies derived from 27 healthy bitches. According to the condition at birth, bitches and their puppies were allocated into either a Eutocia Group (vaginal birth with no whelping assistance), Fetal Dystocia Group (whelping assistance with fetal manipulation), Maternal Dystocia Group (whelping assistance because of partial uterine inertia corrected by oxytocin administration), or Cesarean Section Group (fetal or maternal dystocia bitches subjected to C-section). Maternal blood cortisol and glucose concentrations were analyzed during the perinatal period (prepartum, intrapartum, postpartum, and 1 h after postpartum). Neonatal blood samples were collected within 5 min and 1 h after birth for assessment of cortisol and glucose. Maternal dystocia bitches had higher cortisol concentrations at postpartum than the Fetal Dystocia Group. At 1 h postpartum, the Cesarean Section Group had higher cortisol concentrations compared with fetal dystocia bitches. The Eutocia Group presented increased cortisol concentrations at intrapartum and postpartum, whereas fetal dystocia bitches had higher intrapartum cortisol concentrations than at 1 h postpartum. The Maternal Dystocia Group presented higher postpartum cortisol concentrations than at prepartum and 1 h postpartum. Maternal glucose had a progressive increase throughout peripartum and was higher during postpartum and at 1 h postpartum. C-section bitches had the highest blood glucose concentration. Neonatal cortisol concentrations at birth were higher than 1 h after birth. Fetal dystocia puppies had higher cortisol concentrations, whereas caesarian section puppies had lower cortisol levels. Fetal dystocia and C-section puppies had higher glucose concentrations than the Eutocia Group. In conclusion, maternal dystocia leads to high cortisol concentrations in bitches immediately postpartum, whereas only fetal dystocia causes increased neonatal cortisol concentrations. Moreover, fetal dystocia and C-section are hyperglycemic obstetrical conditions for neonatal puppies; on the other hand, only C-section causes hyperglycemia in bitches.

Neonatal thermal response to childbirth: Vaginal delivery vs. caesarean section

Newborns, regardless of the method of termination of pregnancy, are exposed to the first exogenous stress factors during delivery. The purpose of the study was to evaluate the differences in newborns' thermal response to vaginal (VD) vs caesarean section (CS) delivery. The temperature was measured during the first minutes of life within 122 healthy full-term newborns, on the forehead, chest and upper-back by infrared camera (FLIR T1030sc HD). The lowest temperatures were recorded in the forehead of VD newborns (significantly difference with CS; p < 0.001), the warmest was the chest. A significant correlation was found between the duration of the second stage of natural childbirth and surface temperature and pO2 in the newborn blood. The temperatures of selected body surface areas correlate highly positively, regardless of the mode of delivery. In the case of healthy neonates, with normal birth weight and full-term, VD creates more favourable conditions stimulating the mechanisms of adaptation for a newborn than CS.

A Behavioral Epigenetics Model to Predict Oral Feeding Skills in Preterm Infants

BACKGROUND

Preterm infants experience a multitude of prenatal and postnatal stressors, resulting in cumulative stress exposure, which may jeopardize the timely attainment of developmental milestones, such as achieving oral feeding. Up to 70% of preterm infants admitted to the neonatal intensive care unit experience challenges while initiating oral feeding. Oral feeding skills require intact neurobehavioral development. Evolving evidence demonstrates that cumulative stress exposure results in epigenetic modification of glucocorticoid-related genes. Epigenetics is a field of study that focuses on phenotypic changes that do not involve alterations in the DNA sequence. Epigenetic modification of glucocorticoid-related genes alters cortisol reactivity to environmental stimuli, which may influence neurobehavioral development, and is the essence of the evolving field of Preterm Behavioral Epigenetics. It is plausible that early-life cumulative stress exposure and the ensuing epigenetic modification of glucocorticoid-related genes impair neurobehavioral development required for achievement of oral feeding skills in preterm infants.

PURPOSE

The purpose of this article is to build upon the evolving science of Preterm Behavioral Epigenetics and present a conceptual model that explicates how cumulative stress exposure affects neurobehavioral development and achievement of oral feeding skills through epigenetic modification of glucocorticoid-related genes.

METHODS/RESULTS

Using the Preterm Behavioral Epigenetics framework and supporting literature, we present a conceptual model in which early-life cumulative stress exposure, reflected by DNA methylation of glucocorticoid-related genes and altered cortisol reactivity, disrupts neurobehavioral development critical for achievement of oral feeding skills.

IMPLICATIONS FOR PRACTICE AND RESEARCH

Future investigations guided by the proposed conceptual model will benefit preterm infant outcomes by introducing epigenetic-based approaches to assess and monitor preterm infant oral feeding skills. Furthermore, the proposed model can guide future investigations that develop and test epigenetic protective interventions to improve clinical outcomes, representing an innovation in neonatal care.

Parturition and the perinatal period: can mode of delivery impact on the future health of the neonate?

Caesarean section and instrumental delivery rates are increasing in many parts of the world for a range of cultural and medical reasons, with limited consideration as to how 'mode of delivery' may impact on childhood and long-term health. However, babies born particularly by pre-labour caesarean section appear to have a subtly different physiology from those born by normal vaginal delivery, with both acute and chronic complications such as respiratory and cardio-metabolic morbidities being apparent. It has been hypothesized that inherent mechanisms within the process of labour and vaginal delivery, far from being a passive mechanical process by which the fetus and placenta are expelled from the birth canal, may trigger certain protective developmental processes permissive for normal immunological and physiological development of the fetus postnatally. Traditionally the primary candidate mechanism has been the hormonal surges or stress response associated with labour and vaginal delivery, but there is increasing awareness that transfer of the maternal microbiome to the infant during parturition. Transgenerational transmission of disease traits through epigenetics are also likely to be important. Interventions such as probiotics, neonatal gut seeding and different approaches to clinical care have potential to influence parturition physiology and improve outcomes for infants.