Association between caesarean section and childhood obesity: a systematic review and meta-analysis

Prenatal determinants of childhood obesity: a review of risk factors 1

Childhood obesity is a predictor of adult obesity and has its roots in the pre-pregnancy or pregnancy period. This review presents an overview of the prenatal risk factors for childhood obesity, which were categorized into 2 groups: biological risk factors (maternal pre-pregnancy body mass index, gestational weight gain, diabetes in pregnancy, and caesarean section), and environmental and behavioural risk factors (maternal smoking and exposure to obesogens, maternal dietary patterns, maternal intestinal microbiome and antibiotics exposure, and maternal psychosocial stress). Identifying modifiable predisposing prenatal factors for obesity will inform further development of inventions to prevent obesity over the life course, and future directions for research and intervention are discussed.

Association between cesarean section and constipation in infants: the Japan Environment and Children's Study (JECS)

Objective

There have been increasing reports on the association between cesarean section (C-section) and the subsequent development of diseases in infants. C-section affects the diversity of microbiota in the infant’s gut. In the present study, we investigated the association between infants delivered by C-section and the development of constipation at 1 year old due to altered gut microbiota using data from the Japan Environment and Children’s Study (JECS).

Results

This cohort study (n = 83,019) used data from JECS, an ongoing cohort study which began in January 2011. Data on bowel movement and potential confounding factors were recorded. A log-binomial regression model was used to estimate the risk of C-section, and the results were expressed as risk ratios and their respective 95% confidence intervals. Although infants delivered by C-section were of significantly younger gestational age and lesser birth weight than vaginally delivered infants, the frequency of bowel movements was almost similar between the two, independent of the mode of delivery. The prevalence of constipation in the entire infant was 1.37%. No significant differences were observed for C-section in crude and adjusted risk ratios for constipation.

Factors Influencing the Intestinal Microbiome During the First Year of Life

The intestinal microbiome plays a crucial role in the development of the immune system and regulation of immune responses. Many factors influence the composition of the infant intestinal microbiome and therefore the development and function of the immune system. This, in turn, may alter the risk of subsequent allergies, autoimmune diseases and other adverse health outcomes. Here, we review factors that influence the composition of the intestinal microbiome during the first year of life, including birth location, gestational age, delivery mode, feeding method, hospitalization, antibiotic or probiotic intake and living conditions. Understanding how the early intestinal microbiome is established and how this is perturbed provides many opportunities for interventions to improve health.

Cesarean section and risks of overweight and obesity in school-aged children: a population-based study

BACKGROUND

Obesity puts a great health burden in the world. Previous studies suggest that caesarean section (CS) may increase the risk of obesity in children, but it is still uncertain whether this association is causal or due to residual confounding by medical indication.

AIM

To assess the association between CS, CS without medical indications in particular and the risk of overweight and obesity in school-aged children.

DESIGN

Cross-sectional survey.

METHODS

The 2014 Shanghai Child Health, Education and Lifestyle Evaluation was a large population-based survey with cluster random probability sampling in 26 primary schools in Shanghai, China, in 2014. The mode of delivery was reported by parents. The height, weight and waist circumference of the children were measured. Logistic regression models with SURVEYLOGISTIC procedure were used to estimate the risk of childhood obesity. Pupils delivered vaginally were served as the reference group.

RESULTS

A total of 17 571 pupils completed this survey, and 13 724 of them who were singleton, born term and between 5 and 13 years old were included in our analysis. CS was associated with increased risks of overweight and obesity (BMI: adjusted OR = 1.28 [95%CI 1.13-1.45] and 1.44 [1.26-1.66], respectively; weight for height ratio [WHtR] >0.46: 1.33 [1.20-1.48]). Similar results were found in CS without medical indication (BMI: overweight = 1.24 [1.05-1.47], obesity = 1.43 [1.19-1.72]; WHtR > 0.46: 1.30 [1.13-1.50]).

CONCLUSIONS

CS overall and CS without medical indications were associated with increased risks of overweight and obesity in primary school children.

Moderating effect of mode of delivery on the genetics of intelligence: Explorative genome-wide analyses in ALSPAC

INTRODUCTION

Intelligence is a core construct of individual differences in cognitive abilities and a strong predictor of important life outcomes. Within recent years, rates of cesarean section have substantially increased globally, though little is known about its effect on neurodevelopmental trajectories. Thus, we aimed to investigate the influence of delivery by cesarean section on the genetics of intelligence in children.

METHODS

Participants were recruited through the Avon Longitudinal Study of Parents and Children (ALSPAC). Intelligence was measured by the Wechsler Intelligence Scale for Children (WISC). Genotyping was performed using the Illumina Human Hap 550 quad genome-wide SNP genotyping platform and was followed by imputation using MACH software. Genome-wide interaction analyses were conducted using linear regression.

RESULTS

A total of 2,421 children and 2,141,747 SNPs were subjected to the genome-wide interaction analyses. No variant reached genome-wide significance. The strongest interaction was observed at rs17800861 in the GRIN2A gene (β = -3.43, 95% CI = -4.74 to -2.12, p = 2.98E-07). This variant is predicted to be located within active chromatin compartments in the hippocampus and may influence binding of the NF-kappaB transcription factor.

CONCLUSIONS

Our results may indicate that mode of delivery might have a moderating effect on genetic disposition of intelligence in children. Studies of considerable sizes (>10,000) are likely required to more robustly detect variants governing such interaction. In summary, the presented findings prompt the need for further studies aimed at increasing our understanding of effects various modes of delivery may have on health outcomes in children.

Therapeutic Microbiology: The Role of Bifidobacterium breve as Food Supplement for the Prevention/Treatment of Paediatric Diseases

The human intestinal microbiota, establishing a symbiotic relationship with the host, plays a significant role for human health. It is also well known that a disease status is frequently characterized by a dysbiotic condition of the gut microbiota. A probiotic treatment can represent an alternative therapy for enteric disorders and human pathologies not apparently linked to the gastrointestinal tract. Among bifidobacteria, strains of the species Bifidobacterium breve are widely used in paediatrics. B. breve is the dominant species in the gut of breast-fed infants and it has also been isolated from human milk. It has antimicrobial activity against human pathogens, it does not possess transmissible antibiotic resistance traits, it is not cytotoxic and it has immuno-stimulating abilities. This review describes the applications of B. breve strains mainly for the prevention/treatment of paediatric pathologies. The target pathologies range from widespread gut diseases, including diarrhoea and infant colics, to celiac disease, obesity, allergic and neurological disorders. Moreover, B. breve strains are used for the prevention of side infections in preterm newborns and during antibiotic treatments or chemotherapy. With this documentation, we hope to increase knowledge on this species to boost the interest in the emerging discipline known as "therapeutic microbiology".

Associations of birth mode with cord blood cytokines, white blood cells, and newborn intestinal bifidobacteria

The associations of Cesarean delivery with offspring metabolic and immune-mediated diseases are believed to derive from lack of mother-to-newborn transmission of specific microbes at birth. Bifidobacterium spp., in particular, has been hypothesized to play a health-promoting role, yet little is known about how delivery mode modifies colonization of the newborn by this group of microbes. The aim of this research was to examine the presence of Bifidobacterium in meconium and in the transitional stool, and to assess cytokine levels and hematological parameters in the venous cord blood of infants born by elective, pre-labor Cesarean section vs. vaginal delivery in Southern Brazil. We recruited 89 mother-newborn pairs (23 vaginal delivery and 66 elective cesarean delivery), obtained demographic information from a structured questionnaire and clinical information from medical records. We obtained umbilical cord venous blood and meconium samples following delivery and the transitional stool (the first defecation after meconium) before discharge. We determined plasma levels of IL-1β, IL-10, IL-6, GM-CSF, IL-5, IFN-γ, TNF-α, IL-2, IL-4 and IL-8 in the cord blood, and presence of stool Bifidobacterium by real time PCR. Compared to vaginally-delivered neonates, Cesarean-delivered neonates had a lower leukocyte count (p = 0.037), lower hemoglobin (p = 0.04), and lower levels of the cytokine GM-CSF (p = 0.009) in the cord blood. Moreover, Bifidobacterium was detected less often in the transitional stool of Cesarean-delivered neonates compared to vaginally-delivered neonates (p = 0.001). The results indicate that pre-labor Cesarean birth may be associated with microbial and hematological alterations in the neonate. The clinical significance of these findings remains to be determined in larger prospective birth cohort studies.

Association of Elective and Emergency Cesarean Delivery With Early Childhood Overweight at 12 Months of Age

IMPORTANCE

Global cesarean delivery (CD) rates have more than doubled over the past 2 decades, with an increasing contribution from elective CDs. Cesarean delivery has been linked to early childhood overweight and obesity, but limited studies have examined elective and emergency CDs separately.

OBJECTIVE

To investigate whether elective or emergency CD was associated with risk of early childhood overweight.

DESIGN, SETTING, AND PARTICIPANTS

Data were drawn from the Growing Up in Singapore Toward Healthy Outcomes (GUSTO) study, an ongoing prospective mother-child birth cohort study. Participants were pregnant women aged 18 years or older with homogeneous parental ethnic background in their first trimester recruited between June 2009 and September 2010 (n = 1237) at 2 major public hospitals in Singapore. Those with type 1 diabetes or undergoing chemotherapy or psychotropic drug treatment were excluded. Data analysis commenced in October 2017.

EXPOSURES

Delivery mode obtained from clinical records. Elective and emergency CD examined separately against vaginal delivery as reference.

MAIN OUTCOMES AND MEASURES

Body mass index-for-age z scores at age 12 months calculated based on 2006 World Health Organization Child Growth Standards from infant weight and recumbent crown-heel length measurements taken between December 2010 and April 2012. High body mass index status at risk of overweight was defined as a z score of more than 1 SD and less than or equal to 2 SDs. Overweight was defined as a z score of more than 2 SDs.

RESULTS

Among 727 infants analyzed (51.2% [372] male), 30.5% (222) were born via CD, of which 33.3% (74) were elective. Prevalence of at risk of overweight and overweight at age 12 months was 12.2% (89) and 2.3% (17), respectively. Elective CD was significantly associated with at risk of overweight or overweight at age 12 months after adjusting for maternal ethnicity, age, education, parity, body mass index, antenatal smoking, hypertensive disorders of pregnancy, gestational diabetes, and sex-adjusted birth weight-for-gestational age (odds ratio, 2.05; 95% CI, 1.08-3.90; P = .03). The association persisted after further adjustment for intrapartum antibiotics and first 6 months infant feeding, 2 potential mediators of early childhood overweight and obesity (odds ratio, 2.02; 95% CI, 1.05-3.89; P = .04). No significant associations were found for emergency CD. Analysis with multiple imputation for missing covariates yielded similar results.

CONCLUSIONS AND RELEVANCE

Choice of delivery mode may influence risk of early childhood overweight. Clinicians are encouraged to discuss potential long-term implications of elective CD on child metabolic outcomes with patients who intend to have children.

Developmental programming of aging trajectory

There is accumulating evidence that aging phenotype and longevity may be developmentally programmed. Main mechanisms linking developmental conditions to later-life health outcomes include persistent changes in epigenetic regulation, (re)programming of major endocrine axes such as growth hormone/insulin-like growth factor axis and hypothalamic-pituitary-adrenal axis and also early-life immune maturation. Recently, evidence has also been generated on the role of telomere biology in developmental programming of aging trajectory. In addition, persisting changes of intestinal microbiota appears to be crucially involved in these processes. In this review, experimental and epidemiological evidence on the role of early-life conditions in programming of aging phenotypes are presented and mechanisms potentially underlying these associations are discussed.

Does cesarean delivery impact infant weight gain and adiposity over the first year of life?

Background:

Potentially driven by the lack of mother-to-infant transmission of microbiota at birth, Cesarean delivery has been associated with higher offspring obesity. Yet, no studies have examined when delivery-mode differences in adiposity begin to emerge. In this study, we examine differences in infant weight and adiposity trajectories from birth to 12 months by delivery mode.

Methods:

From 2013 to 2015, we recruited pregnant women into the Nurture Study and followed up their 666 infants. We ascertained maternal delivery method and infant birth weight from medical records. We measured weight, length, and skinfolds (subscapular, triceps, abdominal) when infants were 3, 6, 9 and 12 months of age. The main outcome, infant weight-for-length z score, was derived based on the WHO Child Growth Standards. We used linear regression to assess the difference at each time point and used linear mixed models to examine the growth rate for infant weight and adiposity trajectories. We controlled for maternal age, race, marital status, education level, household income, smoking status, maternal pre-pregnancy body mass index, and infant birth weight.

Results:

Of the 563 infants in our final sample, 179 (31.8%) were Cesarean delivered. From birth to 12 months, the rate of increase in weight-for-length z score was 0.02 units/month (p=0.03) greater for Cesarean-delivered than vaginally-delivered infants. As a result of more rapid growth, Cesarean-delivered infants had higher weight-for-length z score (0.26 units, 95% CI 0.05–0.47) and sum of subscapular and triceps (SS+TR) skinfolds (0.95mm, 95% CI 0.30–1.60)—an adiposity indicator—at 12 months, compared to vaginally-delivered infants.

Conclusion:

Compared to vaginal delivery, Cesarean delivery was associated with greater offspring rate of weight gain over the first year and differences in adiposity that appear as early as 3 months of age. Monitoring Cesarean-delivered infants closely for excess weight gain may help guide primordial prevention of obesity later in life.

Diversified gut microbiota in newborns of mothers with gestational diabetes mellitus

Gestational diabetes mellitus (GDM), a high-risk pregnancy complication of great effect on the perinatal health of women and newborns, may cause changes of gut microbiota in mothers and further affect gut microbiota in newborns. This study aimed to investigate the potential effect of mother GDM on newborns’ gut microbiota. Meconium DNA was extracted from a total of 34 full-term and C-sectioned newborns, in which 20 newborns had mothers diagnosed with GDM, while 14 had unaffected mothers. Sequencing and bioinformatics analysis of 16S rRNA indicated that the gut microbiota of GDM newborns showed differences compared to control newborns. The taxonomy analyses suggested that the overall bacterial content significantly differed by maternal diabetes status, with the microbiome of the GDM group showing lower alpha-diversity than that of control group. The phyla of Proteobacteria and Actinobacteria in GDM newborns increased, while that of Bacteroidetes significantly reduced (P<0.05). Moreover, several unique gut microbiota in phylum of Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, Chloroflexi, Acidobacteria, and Planctomycetes found in control newborns were absent in GDM ones. At genus level, the relative abundance of Prevotella and Lactobacillus significantly decreased (P<0.05) in GDM newborns. Correlation analysis indicated that maternal fasting glucose levels were positively correlated with the relative abundance of phylum Actinobacteria and genus Acinetobacter, while negatively correlated with that of phylum Bacteroidetes and genus Prevotella. However, bacteria in GDM grade A2 (GDM_A2) newborns did not show any statistical variation compared to those from control newborns, which might be attributed to the additional intervention by insulin. The results of this study have important implications for understanding the potential effects of GDM on the gut microbiota of newborns and thus possibly their metabolism at later stages in their lives.

The Impact of Caesarean Section on the Risk of Childhood Overweight and Obesity: New Evidence from a Contemporary Cohort Study

Caesarean section (CS) rates are increasing globally and exceed 50% in some countries. Childhood obesity has been linked to CS via lack of exposure to vaginal microflora although the literature is inconsistent. We investigated the association between CS birth and the risk of childhood obesity using the nationally representative Growing-Up-in-Ireland (GUI) cohort. The GUI study recruited randomly 11134 infants. The exposure was categorised into normal vaginal birth (VD) [reference], assisted VD, elective (planned) CS and emergency (unplanned) CS. The primary outcome measure was obesity defined according to the International Obesity Taskforce criteria. Statistical analysis included multinomial logistic regression with adjustment for potential confounders. Infants delivered by elective CS had an adjusted relative risk ratio (aRRR) = 1.32; [95% confidence interval (CI) 1.01-1.74] of being obese at age three years. This association was attenuated when macrosomic children were excluded (aRRR = 0.99; [95% CI 0.67-1.45]). Infants delivered by emergency CS had an increased risk of obesity aRRR = 1.56; [95% CI 1.20-2.03]; this association remained after excluding macrosomic children. We found insufficient evidence to support a causal relationship between elective CS and childhood obesity. An increased risk of obesity in children born by emergency CS, but not elective, suggests that there is no causal effect due to vaginal microflora.

Association between provider type and cesarean birth in healthy nulliparous laboring women: A retrospective cohort study

BACKGROUND

Term nulliparous women have the greatest variation across hospitals and providers in cesarean rates and therefore present an opportunity to improve quality through optimal care. We evaluated associations between provider type and mode of birth, including examination of intrapartum management in healthy, laboring nulliparous women.

METHODS

Retrospective cohort study using prospectively collected perinatal data from a United States academic medical center (2005-2012). The sample included healthy nulliparous women with spontaneous labor onset and term, singleton, vertex fetus managed by either obstetricians or certified nurse-midwives. Univariate and multivariate logistic regression was used to compare labor interventions and mode of birth by provider type.

RESULTS

A total of 1339 women received care by an obstetrician (n = 749) or nurse-midwife (n = 590). The cesarean rate was 13.4% (179/1339). Adjusting for maternal and pregnancy characteristics, care by obstetricians was associated with an increased risk of unplanned cesarean birth (adjusted odds ratio [aOR] 1.48 [95% confidence interval {CI} 1.04-2.12]) compared with care by midwives. Obstetricians more frequently used oxytocin augmentation (aOR 1.41 [95% CI 1.10-1.80]), neuraxial anesthesia (aOR 1.69 [95% CI 1.29-2.23]), and operative vaginal delivery with forceps or vacuum (aOR 2.79 [95% CI 1.75-4.44]). Adverse maternal or neonatal outcomes were not different by provider type across all modes of birth, but were more frequent in women with cesarean than vaginal births.

DISCUSSION

In low-risk nulliparous laboring women, care by obstetricians compared with nurse-midwives was associated with increased risk of labor interventions and operative birth. Changes in labor management or increased use of nurse-midwives could decrease the rate of a first cesarean in low-risk laboring women.

Three-Month Feeding Integration With Bifidobacterium Strains Prevents Gastrointestinal Symptoms in Healthy Newborns

Infantile functional gastrointestinal disorders are common in the first months of life. Their pathogenesis remains unknown although evidences suggest multiple independent causes, including gut microbiota modifications. Feeding type, influencing the composition of intestinal microbiota, could play a significant role in the pathogenesis. Previous studies supported probiotic supplementation success against colics, however mainly Lactobacillus spp. were tested. The aim of this study was to evaluate the effectiveness against functional gastrointestinal disorders of a Bifidobacterium breve based probiotic formulation including in the study both breast-fed and bottle-fed subjects. Two hundred and sixty-eight newborns were enrolled within 15 days from birth. One hundred and fifty-five of them effectively entered the study and were randomized in probiotic and placebo group, receiving the formulation for 90 days. The probiotic formulation consists of a 1:1 mixture of 2 strains of B. breve prepared in an oily suspension and administered in a daily dosage of 5 drops containing 108 CFU of each strain. Absolute quantification of selected microbial groups in the faeces was performed using qPCR. Anthropometric data, daily diary minutes of crying, number of regurgitations, vomits and evacuations, and colour and consistency of stools were evaluated before and after treatment. The study confirmed the positive role of breast milk in influencing the counts of target microbial groups, in particular the bifidobacteria community. No adverse events upon probiotic administration were reported, suggesting the safety of the product in this regimen. B. breve counts increased significantly in all administered newborns (p < 0.02). The study demonstrates that a 3 months treatment with B. breve strains in healthy breast-fed newborns helps to prevent functional gastrointestinal disorders, in particular reducing 56% of daily vomit frequency (p < 0.03), decreasing 46.5% of daily evacuation over time (p < 0.03), and improving the stool consistency (type 6 at the Bristol Stool chart instead of type 5) in those at term (p < 0.0001). Moreover, a significant reduction (8.65 vs. 7.98 LogCFU/g of feces, p < 0.03) of B. fragilis in the bottle-fed group receiving the probiotic formulation was observed.

Childhood obesity in Mexico: social determinants of health and other risk factors

Approximately 50 million children and adolescents in Latin America are affected by the childhood obesity pandemic. We present the case of a 5-year-old Mexican girl with obesity and gastro-oesophageal reflux disease (GORD), in whom prenatal, lifestyle and environmental risk factors were identified. Here, we demonstrate how childhood obesity is rooted since pregnancy and the perinatal stage, and how the social determinants of health like unsafe outdoor conditions, lack of infrastructure to exercise and a suboptimal physical activity curriculum in government schools strongly influence the development and maintenance of childhood obesity and complicate management.

Duration of Breastfeeding, but Not Timing of Solid Food, Reduces the Risk of Overweight and Obesity in Children Aged 24 to 36 Months: Findings from an Australian Cohort Study

This study aimed to determine whether breastfeeding duration and the timing of solid food were independently associated with being overweight or obese in early childhood. Subjects were 953 children participating in the Study of Mothers and Infants Life Events Affecting Oral Health (SMILE) birth cohort study, based in Adelaide, Australia. Socio-demographic information and data on breastfeeding duration and age of introduction of solid food were collected at birth, 3, 4, 6, 12, and 24 months via mailed or online questionnaires completed by mothers. The weight and height of children were measured at a dental examination when children were aged between 24 and 36 months. Body mass index was calculated, and children were categorised into weight groups according to the World Health Organization growth standards. Multivariable logistic regression analysis was conducted, adjusting for maternal age at birth, education, socio-economic status, pre-pregnancy weight, smoking in pregnancy, method of delivery, and child’s birthweight. Risk of overweight/obesity was independently associated with maternal pre-pregnancy BMI, smoking in pregnancy, and birthweight. Children that were breastfed for 12 months or more had a significantly lower risk of being overweight/obese than those breastfed for less than 17 weeks (AOR 0.49; 95%CI 0.27, 0.90; p for trend =0.009). Age of introduction of solid food, however, was not associated with the risk of being overweight/obese at 24 to 36 months. This study provides further evidence of an inverse relationship between breastfeeding and risk of overweight/obesity, however, no association with the timing of solid food was detected.

Initial meconium microbiome in Chinese neonates delivered naturally or by cesarean section

Previous studies have revealed significant differences in microbiome compositions between infants delivered via cesarean section (C-section) and natural vaginal birth. However, the importance of the delivery mode in the first days of life remains unclear. Importantly, this stage is minimally affected by infant feeding. Here, we used a metagenomic sequencing technique to characterize the meconium microbiome from the feces of a Chinese cohort of vaginally and C-section-delivered infants, including in vitro fertilization (IVF) newborns, during the first 24 h after birth. Meconium microbiome diversity was higher in vaginally delivered infants than that in C-section-delivered infants. Propionibacterium species were most abundant in the vaginally delivered infants, whereas the C-section group had high levels of Bacillus licheniformis. The two IVF newborns delivered by C-section harbored microbial communities similar to the vaginal microbiome in terms of taxonomic composition. Metabolic functions of the C-section group suffered more from the influence of the dominant group (B. licheniformis), whereas the vaginal group was more homogeneous, with a metabolism dominated by multi-microbes. Moreover, different modes of delivery affected the antibiotic resistance gene (ARG) prevalence. These findings provide novel information for the development of strategies to guide a healthy mode of delivery and promote the formation of healthy microbiota.

Characterization of the Stool Microbiome in Hispanic Preschool Children by Weight Status and Time

BACKGROUND

Variations in gut microbiota composition and diversity have been associated with childhood adiposity, although most studies describing this have been cross-sectional in nature. Our objective was to evaluate associations between body weight and the gut microbiota over time in obese preschool-age children.

METHODS

Obese, preschool-age, Hispanic children provided stool samples at baseline and following a 6-month behavioral intervention. Normal-weight (NW) children also provided stool samples. Stool microbial community composition was characterized using 16S rRNA gene sequencing. Estimates of within-sample diversity were calculated on operational taxonomic unit (OTU) count data, and the Firmicutes:Bacteroidetes (F:B) ratio was determined on per-sample basis. Estimates of between-sample diversity were generated using the weighted Unifrac metric, differential abundances were evaluated using Wilcoxon rank-sum tests, and associations of microbiome features with clinical data were quantified using Spearman rank correlations.

RESULTS

For the 30 obese children sampled preintervention and postintervention, a decrease in body mass index (BMI) z-score from 2.55 to 2.34 (p = 0.004, paired t-test) was observed. Bacteroides massiliensis was significantly enriched in obese children, while B. plebius was significantly enriched in NW controls. We identified significant correlations between multiple Bacteroides-like OTUs and BMI z-score, but neither F:B ratios nor OTU-level abundances were altered in conjunction with weight change in the obese children. Rather, highly individualized OTU-level responses were observed.

CONCLUSIONS

Although differences exist between the gut microbiota of obese and NW children, we detected highly individualized responses of the gut microbiota of obese children over time and following weight loss.

Fungi as Part of the Microbiota and Interactions with Intestinal Bacteria

The human microbiota consists of bacteria, archaea, viruses, and fungi that build a highly complex network of interactions between each other and the host. While there are many examples for commensal bacterial influence on host health and immune modulation, little is known about the role of commensal fungi inside the gut community. Up until now, fungal research was concentrating on opportunistic diseases caused by fungal species, leaving the possible role of fungi as part of the microbiota largely unclear. Interestingly, fungal and bacterial abundance in the gut appear to be negatively correlated and disruption of the bacterial microbiota is a prerequisite for fungal overgrowth. The mechanisms behind bacterial colonization resistance are likely diverse, including direct antagonism as well as bacterial stimulation of host defense mechanisms. In this work, we will review the current knowledge of the development of the intestinal bacterial and fungal community, the influence of the microbiota on human health and disease, and the role of the opportunistic yeast C. albicans. We will furthermore discuss the possible benefits of commensal fungal colonization. Finally, we will summarize the recent findings on bacterial-fungal interactions.

Gut Microbiota in Obesity and Metabolic Abnormalities: A Matter of Composition or Functionality?

The obesity pandemic and the metabolic complications derived from it represent a major public health challenge worldwide. Although obesity is a multifactorial disease, research from the past decade suggests that the gut microbiota interacts with host genetics and diet, as well as with other environmental factors, and thus contributes to the development of obesity and related complications. Despite abundant research on animal models, substantial evidence from humans has only started to accumulate over the past few years. Thus, the aim of the present review is to discuss structural and functional characteristics of the gut microbiome in human obesity, challenges associated with multi-omic technologies, and advances in identifying microbial metabolites with a direct link to obesity and metabolic complications. To date, studies suggests that obesity is related to low microbial diversity and taxon depletion sometimes resulting from an interaction with host dietary habits and genotype. These findings support the idea that the depletion or absence of certain taxa leaves an empty niche, likely leading to compromised functionality and thus promoting dysbiosis. Although the role of altered gut microbiota as cause or consequence of obesity remains controversial, research on microbial genomes and metabolites points towards an increased extraction of energy from the diet in obesity and suggests that metabolites, such as trimethylamine-N-oxide or branched-chain amino acids, participate in metabolic complications. Future research should be focused on structural and functional levels to unravel the mechanism linking gut microbiota and obesity.

Association between Cesarean Section and Weight Status in Chinese Children and Adolescents: A National Survey

Previous research on the association between cesarean section (CS) and childhood obesity has yielded inconsistent findings. This study assessed the secular trend of CS and explored the relationship between CS and the risks of overweight and obesity in Chinese children and adolescents. Data came from a national multicenter school-based study conducted in seven provinces of China in 2013. Covariate data including weight, height and delivery mode were extracted. Poisson regression was applied to determine the risk ratios (RRs) and 95% confidence intervals (CIs) for the risks of overweight and obesity associated with the delivery mode. A total of 18,780 (41.2%) subjects were born by CS between 1997 and 2006. The rate of CS increased from 27.2% in 1997 to 54.1% in 2006. After adjusting for major confounders, the RRs (95% CI) of overweight and obesity among subjects born by CS were 1.21 (1.15 to 1.27) and 1.51 (1.42 to 1.61), respectively. Similar results were observed in different subgroups stratified by sex, age, and region. In summary, the CS rate increased sharply in China between 1997 and 2006. CS was associated with increased risks of overweight and obesity in offspring after accounting for major confounding factors.

The Brain-Derived Neurotrophic Factor Val66Met Polymorphism, Delivery Method, Birth Weight, and Night Sleep Duration as Determinants of Obesity in Vietnamese Children of Primary School Age

BACKGROUND

Obesity is a complex disease that involves both environmental and genetic factors in its pathogenesis. Several studies have identified multiple obesity-associated loci in many populations. However, their contribution to obesity in the Vietnamese population is not fully described, especially in children. The study aimed to investigate the association of obesity with Val66Met polymorphism in brain-derived neurotrophic factor (BDNF) gene, delivery method, birth weight, and lifestyle factors in Vietnamese primary school children.

METHODS

A case-control study was conducted on 559 children aged 6-11 years (278 obese cases and 281 normal controls). The obesity of the children was classified using both criteria of International Obesity Task Force (IOTF, 2000) and World Health Organization (WHO, 2007). Lifestyle factors, birth delivery, and birth weight of the children were self-reported by parents. The BDNF genotype was analyzed using the polymerase chain reaction-restriction fragment length polymorphism method. Association was evaluated by multivariate logistic regression and cross-validated by the Bayesian model averaging method.

RESULTS

The most significantly independent factors for obesity were delivery method (cesarean section vs. vaginal delivery, β = 0.56, p = 0.007), birth weight (>3500 to <4000 g vs. 2500-3500 g, β = 0.52, p = 0.035; ≥4000 g vs. 2500-3500 g, β = 1.06, p = 0.015), night sleep duration (<8 h/day vs. ≥8 h/day, β = 0.99, p < 0.0001), and BDNF Val66Met polymorphism (AA and GG vs. AG, β = 0.38, p = 0.039).

CONCLUSIONS

The study suggested the significant association of delivery method, birth weight, night sleep duration, and BDNF Val66Met polymorphism, with obesity in Vietnamese primary school children.

Microbes in Infant Gut Development: Placing Abundance Within Environmental, Clinical and Growth Parameters

Sound and timely microbial gut colonization completes newborn’s healthy metabolic programming and manifests in infant appropriate growth and weight development. Feces, collected at 3, 30, and 90 days after birth from 60 breastfed Slovenian newborns, was submitted to microbial DNA extraction and qPCR quantification of selected gut associated taxa. Multivariate regression analysis was applied to evaluate microbial dynamics with respect to infant demographic, environmental, clinical characteristics and first year growth data. Early microbial variability was marked by the proportion of Bacilli, but diminished and converged in later samples, as bifidobacteria started to prevail. The first month proportions of enterococci were associated with maternity hospital locality and supplementation of breastfeeding with formulae, while Enterococcus faecalis proportion reflected the mode of delivery. Group Bacteroides-Prevotella proportion was associated with infant weight and ponderal index at first month. Infant mixed feeding pattern and health issues within the first month revealed the most profound and extended microbial perturbations. Our findings raise concerns over the ability of the early feeding supplementation to emulate and support the gut microbiota in a way similar to the exclusively breastfed infants. Additionally, practicing supplementation beyond the first month also manifested in higher first year weight and weight gain Z-score.

The Elevated Rate of Cesarean Section and Its Contribution to Non-Communicable Chronic Diseases in Latin America: The Growing Involvement of the Microbiota

The current recommendation of the World Health Organization (WHO) regarding cesarean section (C-section) is that this clinical practice should be carried out only under specific conditions, when the health or life of the mother/newborn dyad is threatened, and that its use should not exceed 10-15% of the total deliveries. However, over the last few decades, the frequency of C-section delivery in medium- and high-income countries has rapidly increased worldwide. This review describes the evolution of this procedure in Latin American countries, showing that today more than half of newborns in the region are delivered by C-section. Given that C-section delivery is more expensive than vaginal delivery, its use has increased more rapidly in the private than the public sector; nevertheless, the prevalence of C-section deliveries in the public sector is higher than the WHO's recommendations and continues to increase, representing a growing challenge for Latin America. Although the medium- and long-term consequences of C-section delivery, as opposed to vaginal delivery, on the infant health are unclear, epidemiological studies suggest that it is associated with higher risk of developing asthma, food allergy, type 1 diabetes, and obesity during infancy. These findings are important, as the incidence of these diseases in the Latin American pediatric population is also increasing, particularly obesity. Although the link between these diseases and delivery mode remains controversial, recent studies indicate that the establishment of the gut microbiota is delayed in infants born by C-section during the postnatal period, i.e., during a critical developmental window for the maturation of the newborn's immune system. This delay may favor the subsequent development of inflammatory and metabolic disorders during infancy. Accordingly, from a public health perspective, it is important to slow down and eventually reverse the pattern of increased C-section use in the affected populations.

Caesarean Section Does Not Increase the Risk of Caries in Swedish Children

Caesarean section has been shown to affect the health of the child. Only a few studies have investigated whether the mode of delivery is associated with dental caries, and they present conflicting results. Our study investigated whether dental caries was associated with delivery method in Swedish preschool children. This retrospective register-based cohort study included all children born from 2000 to 2003 who were residing in Stockholm County, Sweden, at 3 y of age (n = 83,147). The study followed the cohort until individuals were 7 y of age. Children examined at 3 and 7 y constituted the final study cohort (n = 65,259). We dichotomized the key exposure “delivery starts by caesarean section” and analyzed it in univariate analyses as well as in multivariate analyses. The multivariate analyses used 3 outcomes: caries experience at age 3 (deft >0 [decayed, extracted, and filled teeth]), caries increment between 3 and 7 y of age (Δdeft > 0), and caries experience at age 7 (deft > 0). Of the final cohort, 15% (n = 9,587) were delivered by caesarean section. At 3 y of age, the results showed no statistically significant association between caesarean section and caries experience (odds ratio = 0.92, 95% confidence interval [CI] = 0.82 to 1.04). Between 3 and 7 y of age, the association of caesarean section on caries increment was 0.88 (95% CI = 0.83 to 0.94) and at 7 y of age, 0.88 (caries experience; 95% CI = 0.82 to 0.94). Higher mean values for caries experience and caries increment were observed in vaginally delivered children. We found that preschool children who were delivered by caesarean section do not represent a group with an excess risk of developing dental caries. Furthermore, the statistically significant associations with caries increment and caries experience at age 7 were negative.

Knowledge Transfer Statement: Children born by caesarean section are at greater risk of developing asthma and obesity. The proportion of elective caesarean sections without a medical indication has increased over the years; therefore, it is important to know how this mode of delivery affects oral health of the child. The results show that children who are delivered by caesarean section are not at greater risk of developing dental caries, and clinicians can use these findings in their risk assessment.

Factors Influencing the Gut Microbiota, Inflammation, and Type 2 Diabetes

The gut microbiota is a complex community of bacteria residing in the intestine. Animal models have demonstrated that several factors contribute to and can significantly alter the composition of the gut microbiota, including genetics; the mode of delivery at birth; the method of infant feeding; the use of medications, especially antibiotics; and the diet. There may exist a gut microbiota signature that promotes intestinal inflammation and subsequent systemic low-grade inflammation, which in turn promotes the development of type 2 diabetes. There are preliminary studies that suggest that the consumption of probiotic bacteria such as those found in yogurt and other fermented milk products can beneficially alter the composition of the gut microbiome, which in turn changes the host metabolism. Obesity, insulin resistance, fatty liver disease, and low-grade peripheral inflammation are more prevalent in patients with low α diversity in the gut microbiome than they are in patients with high α diversity. Fermented milk products, such as yogurt, deliver a large number of lactic acid bacteria to the gastrointestinal tract. They may modify the intestinal environment, including inhibiting lipopolysaccharide production and increasing the tight junctions of gut epithelia cells.

Caesarean section and adiposity at 6, 18 and 30 years of age: results from three Pelotas (Brazil) birth cohorts

Background

Association between caesarian section (C-section) and obesity is controversial and mostly based on body mass index (BMI), which has inherent limitations. Using direct estimates of body fat mass, we aimed to assess the association between C-section and adiposity using fat mass index and BMI z-score in three birth cohort studies from Pelotas, Brazil.

Methods

We measured weight, height and fat mass (using dual X-ray absorptiometry (DXA)) at ages 6, 18 and 30 years among participants in the 2004, 1993 and 1982 population-based Pelotas Birth Cohort Studies, respectively. We used multiple linear regression analysis to examine the crude and adjusted association between C-section and the body composition indicators. We also modelled height as an outcome to explore the presence of residual confounding.

Results

We observed that fat mass index and BMI z-score were strongly and positively associated with C-section in the crude analysis. However, when we adjusted for socioeconomic characteristics, maternal BMI, parity, age and smoking during pregnancy, effect estimates were attenuated towards the null, except for 30-year-old women. In those women from the 1982 cohort, C-section remained associated with fat mass index (β = 0.82; CI95% 0.32;1.32) and BMI z-score (β = 0.15; CI95% 0.03;0.28), even after adjusting for all potential confounders, suggesting an increase in fat mass index and BMI at 30 years among those born by C-section.

Conclusion

We found no consistent association of C-section with fat mass index measured by DXA and BMI z-score in individuals aged 6, 18 and 30 years, except for women in the latter group, which might be explained by residual confounding. Confounding by socioeconomic and maternal characteristics accounted for all the other associations.

Associations of prenatal and childhood antibiotic use with child body mass index at age 3 years

OBJECTIVE

Early-life antibiotic exposure, whether through prenatal or childhood antibiotic use, may contribute to increased child body mass. Associations of prenatal and childhood antibiotic use with body mass index z-score (BMIz) were evaluated at age 3 years.

METHODS

Electronic health records were utilized from 8,793 mothers and singleton children delivered at Geisinger Clinic in Pennsylvania between 2006 and 2012. Antibiotic orders were ascertained for mothers during pregnancy and for children through their age-3 BMI measurement. Linear mixed-effects regression models evaluated associations of prenatal and childhood antibiotic use with child BMIz.

RESULTS

Prenatal antibiotic orders were not associated with child BMIz. Children in the three largest categories of lifetime antibiotic orders had higher BMIz compared with children with no orders; associations persisted when controlling for prenatal antibiotics (β [95% confidence interval]) (4-5 child orders: 0.090 [0.011 to 0.170]; 6 to 8: 0.113 [0.029 to 0.197]; ≥9: 0.175 [0.088 to 0.263]; trend P value <0.001). Two or more first-year orders were also associated with BMIz (1: 0.021 [-0.038 to 0.081]; 2: 0.088 [0.017 to 0.160]; ≥3: 0.104 [0.038 to 0.170]; trend P value < 0.001).

CONCLUSIONS

Associations of early-life and lifetime childhood antibiotic use with increased child BMI highlight antibiotic exposure as a modifiable factor for reducing population-level excess weight.

Embracing the gut microbiota: the new frontier for inflammatory and infectious diseases

The gut microbiota provides essential signals for the development and appropriate function of the immune system. Through this critical contribution to immune fitness, the gut microbiota has a key role in health and disease. Recent advances in the technological applications to study microbial communities and their functions have contributed to a rapid increase in host-microbiota research. Although it still remains difficult to define a so-called 'normal' or 'healthy' microbial composition, alterations in the gut microbiota have been shown to influence the susceptibility of the host to different diseases. Current translational research combined with recent technological and computational advances have enabled in-depth study of the link between microbial composition and immune function, addressing the interplay between the gut microbiota and immune responses. As such, beneficial modulation of the gut microbiota is a promising clinical target for many prevalent diseases including inflammatory bowel disease, metabolic abnormalities such as obesity, reduced insulin sensitivity and low-grade inflammation, allergy and protective immunity against infections.

Epigenetic Matters: The Link between Early Nutrition, Microbiome, and Long-term Health Development

Epigenetic modifications are among the most important mechanisms by which environmental factors can influence early cellular differentiation and create new phenotypic traits during pregnancy and within the neonatal period without altering the deoxyribonucleic acid sequence. A number of antenatal and postnatal factors, such as maternal and neonatal nutrition, pollutant exposure, and the composition of microbiota, contribute to the establishment of epigenetic changes that can not only modulate the individual adaptation to the environment but also have an influence on lifelong health and disease by modifying inflammatory molecular pathways and the immune response. Postnatal intestinal colonization, in turn determined by maternal flora, mode of delivery, early skin-to-skin contact and neonatal diet, leads to specific epigenetic signatures that can affect the barrier properties of gut mucosa and their protective role against later insults, thus potentially predisposing to the development of late-onset inflammatory diseases. The aim of this review is to outline the epigenetic mechanisms of programming and development acting within early-life stages and to examine in detail the role of maternal and neonatal nutrition, microbiota composition, and other environmental factors in determining epigenetic changes and their short- and long-term effects.

Cesarean Delivery, Overweight throughout Childhood, and Blood Pressure in Adolescence

OBJECTIVES

To investigate whether children delivered by cesarean had a higher risk of being overweight from early until late childhood and whether they had a higher blood pressure in adolescence compared with children delivered vaginally.

STUDY DESIGN

We used data from a Dutch birth cohort study with prenatal inclusion in 1996 and 1997. Mode of delivery (cesarean or vaginal delivery) was ascertained at 3 months after birth by questionnaire. During clinical examinations, height and weight (at age 4, 8, 12, and 16 years) and blood pressure (at age 12 and 16 years) were measured. We used mixed model analysis to estimate associations of cesarean delivery with overweight and blood pressure z scores in 2641 children who participated in at least 1 of the 4 examinations.

RESULTS

Children born by cesarean delivery (n = 236, 8.9%) had a 1.52 (95% CI 1.18, 1.96) higher odds of being overweight throughout childhood than children delivered vaginally. Children born by cesarean delivery had no higher systolic blood pressure z-score (0.11 SD, 95% CI -0.04, 0.26), nor a different diastolic blood pressure z-score (-0.00 SD, 95% CI -0.10, 0.09) in adolescence than children delivered vaginally.

CONCLUSIONS

Compared with children delivered vaginally, children delivered by cesarean had a 52% higher risk of being overweight throughout childhood, but this was not accompanied by a higher blood pressure in adolescence.

Cesarean section may increase the risk of both overweight and obesity in preschool children

Background

The increase rates of cesarean section (CS) occurred at the same period as the dramatic increase of childhood overweight/obesity. In China, cesarean section rates have exponentially increased in the last 20 years and they now exceed World Health Organization (WHO) recommendation. Such high rates demand an understanding to the long-term consequences on child health. We aim to examine the association between CS and risk of overweight and obesity among preschool children.

Method

We recruited 9103 children from 35 kindergartens in 4 cities located in East China. Children anthropometric measurements were taken in person by trained personnel. The mode of delivery was classified as vaginal or CS, in sub-analyses we divided cesarean delivery into elective or non-elective. The mode of delivery and other parental information were self-reported by parents. Multivariate logistic regression analysis was used to examine the associations.

Results

In our cross-sectional study of 8900 preschool children aged 3–6 years, 67.3 % were born via CS, of whom 15.7 % were obese. Cesarean delivery was significantly associated with the risk of overweight [OR 1.24; (95 % CI 1.07–1.44); p = 0.003], and the risk of obesity [OR 1.29; (95 % CI 1.13–1.49); p < 0.001] in preschool children. After adjusted for child characteristics, parental factors and family income, the odd of overweight was 1.35 and of obesity was 1.25 in children delivered by elective CS.

Conclusion

The associations between CS and overweight/obesity in preschool children are influenced by potential confounders. Both children delivered by elective or non-elective CS are at increased risk of overweight/obesity. Potential consequences of CS on the health of the children should be discussed among both health care professionals and childbearing women.

Born in Brazil: shining a light for change

The Birth in Brazil study is the largest national hospital-based survey in Brazil regarding birth practices. Conducted in 2011–2012, it collected information from 266 public and private healthcare facilities and interviewed nearly 24,000 postpartum women. It is also the latest effort to map out how labor and delivery are managed in this county in the 21st century. The journal Reproductive Health has published a supplement including 10 articles presenting the results of a series of analyses using this valuable resource.

These articles describe a range of practices, determinants and risk factors that affect women and their babies in Brazil, a country of paradoxes. In the era of overmedicalization and high-tech medicine – arguably –, these articles highlight the unprecedented rates of cesarean sections in Brazil and differences between the public and the private sectors. It provides evidence for the need for adequate human resources, medications and emergency care equipment in many settings; and explains the use of non-evidence based interventions during labor and delivery. On the other hand, these studies also point to promising interventions that could be used to change this situation not only in Brazil but also in other countries facing similar challenges.

Childhood body mass is positively associated with cesarean birth in Yucatec Maya subsistence farmers

OBJECTIVE

The epidemiologic link between cesarean birth and childhood obesity is unresolved, partly because most studies come from industrialized settings where many post-birth factors affect the risk for obesity. We take advantage of an unusual ethnographic situation where hospital and cesarean birth modes have recently been introduced among Yucatec Maya subsistence farmers, but young children have had minimal exposure to the nutritional transition. While we expect to find very low rates of childhood obesity, we predict that cesarean-born children will be larger and heavier than vaginally born children.

METHODS

Weight and height were collected monthly on 108 children aged 0-5 (3576 observations total). Birth mode and birthweight were collected by maternal interview. Data were analyzed using linear mixed models that compare child growth [Maya population-specific Z-scores for weight-for-age and body mass index-for-age (WAZ and BMIZ)] in cesarean and vaginally born children aged 0-5 years.

RESULTS

The cesarean rate was 20%, no children were obese, and 5% were overweight. Cesarean birth was a significant predictor of child WAZ and BMIZ after accounting for maternal effects, child birthweight, and sex. Children who were born by cesarean to mothers with high BMI had the highest WAZ of all children by 5 years of age, and the highest BMIZ of all children at all ages.

CONCLUSION

Cesarean-born Maya children had higher BMI than vaginally born children, even in the absence of many known confounding factors that contribute to childhood obesity. Child growth was most sensitive to birth mode when mothers had high BMI.

Type of Labour in the First Pregnancy and Cumulative Perinatal Morbidity

OBJECTIVE

To estimate cumulative perinatal morbidity among infants delivered at term, according to the type of labour in the first pregnancy, when the first pregnancy was low risk.

METHODS

In a 26-year population-based cohort study (1988-2013) using the Nova Scotia Atlee Perinatal Database, we identified the type of labour in successive pregnancies in low-risk, nulliparous women at term in their first pregnancy (who had at least one subsequent pregnancy), and also identified perinatal outcomes in subsequent deliveries according to the type of labour in the first pregnancy.

RESULTS

A total of 37 756 pregnancies satisfied inclusion and exclusion criteria; of these, 1382 (3.7%) had a Caesarean section without labour in the first pregnancy. Rates of most adverse perinatal outcomes were low (≤ 1%). The risks for stillbirth were low in subsequent deliveries, including those that followed CS without labour in the first pregnancy, and the risks for the overall severe perinatal morbidity outcome were less than 10% for all subsequent deliveries.

CONCLUSION

The absolute risks for severe perinatal morbidity outcomes in a population of low-risk women (with up to four additional pregnancies) were small, regardless of type of labour in the first pregnancy. This finding provides important information on perinatal outcomes in subsequent pregnancies when considering type of labour in the first pregnancy.

Early-life exposures to persistent organic pollutants in relation to overweight in preschool children

Current knowledge on obesogenic effects of persistent organic pollutants (POPs) is equivocal. We therefore evaluated the associations between early-life POP exposures and body mass index (BMI) in 444 Faroese children born in 2007-2009. POPs were measured in maternal 2-week postpartum serum and child age-5 serum. Linear regression and generalised linear models assessed the associations with continuous and dichotomous BMI z-scores, respectively, at ages 18 months and/or 5 years. Maternal serum concentrations of HCB, PFOS and PFOA were associated with increased BMI z-scores and/or overweight risk (i.e. BMI z-score≥85th WHO percentile). No clear association was found for maternal serum-PCBs, p,p'-DDE, PFHxS, PFNA and PFDA. In cross-sectional analyses, we observed a pattern of inverse associations between child serum-POPs and BMI z-scores at age 5, perhaps due to reverse causation that requires attention in future prospective analyses. Findings in this recent cohort support a role of maternal exposure to endocrine disruptors in the childhood obesity epidemic.

The Role of the Gut Microbiota in Childhood Obesity

BACKGROUND

Childhood and adolescent obesity has reached epidemic proportions worldwide. The pathogenesis of obesity is complex and multifactorial, in which genetic and environmental contributions seem important. The gut microbiota is increasingly documented to be involved in the dysmetabolism associated with obesity.

METHODS

We conducted a systematic search for literature available before October 2015 in the PubMed and Scopus databases, focusing on the interplay between the gut microbiota, childhood obesity, and metabolism.

RESULTS

The review discusses the potential role of the bacterial component of the human gut microbiota in childhood and adolescent-onset obesity, with a special focus on the factors involved in the early development of the gut bacterial ecosystem, and how modulation of this microbial community might serve as a basis for new therapeutic strategies in combating childhood obesity. A vast number of variables are influencing the gut microbial ecology (e.g., the host genetics, delivery method, diet, age, environment, and the use of pre-, pro-, and antibiotics); but the exact physiological processes behind these relationships need to be clarified.

CONCLUSIONS

Exploring the role of the gut microbiota in the development of childhood obesity may potentially reveal new strategies for obesity prevention and treatment.

The mode of delivery affects the diversity and colonization pattern of the gut microbiota during the first year of infants' life: a systematic review

Background

The human gut is the habitat for diverse and dynamic microbial ecosystem. The human microbiota plays a critical role in functions that sustain health and is a positive asset in host defenses. Establishment of the human intestinal microbiota during infancy may be influenced by multiple factors including delivery mode. Present review compiles existing evidences on the effect of delivery mode on the diversity and colonization pattern of infants gut microbiota.

Methods

Two investigators searched for relevant scientific publications from four databases (Pubmed, Medline, Embase, and Web of Science). The last search was performed on September 21, 2015, using key terms ((delivery mode OR caesarean delivery OR cesarean section OR vaginal delivery) AND (gut microbiota OR gut microbiome OR gut microflora OR intestinal microflora OR microbial diversity) AND (infants OR children)). All included studies described at least two types of gut microbiota in relation to delivery mode (caesarean section vs vaginal delivery) and used fecal samples to detect gut microbiota.

Results

Seven out of 652 retrieved studies met inclusion criteria, were included in systematic analysis. Caesarean Section (CS) was associated with both lower abundance and diversity of the phyala Actinobacteria and Bacteroidetes, and higher abundance and diversity of the phylum Firmicute from birth to 3 months of life. At the colonization level, Bifidobacterium, and Bacteroides genera seems to be significantly more frequent in vaginally delivered infants compared with CS delivered. These infants were more colonized by the Clostridium, and Lactobacillus genera. From the reports, it is tempting to say that delivery mode has less effect on colonization and diversity of Bifidobacteria, Bacteroides, Clostridium, and Lactobacillus genera from the age of 6 to 12 months of life.

Conclusion

The diversity and colonization pattern of the gut microbiota were significantly associated to the mode of delivery during the first three months of life, however the observed significant differences disappears after 6 months of infants life. The healthy gut microbiota is considered to promote development and maturation of the immune system while abnormal gut is considered as the major cause of severe gastrointestinal infections during the infancy. Further studies should investigate the diversity and colonization levels of infant gut microbiota in relation to the mode of delivery and its broad impact on infants’ health at each stage of life.

The Bacterial Microbiome and Virome Milestones of Infant Development

The human gut harbors a complex community of bacteria, viruses, fungi, protists, and other microorganisms (collectively termed the microbiome) that impact health and disease. Emerging studies indicate that the gut bacterial microbiome and virome play an important role in healthy infant development. In turn, the composition of the microbiome during development can be influenced by factors such as dietary, environmental, and maternal conditions. As such, the microbiome trajectory during early infancy could be predictors of healthy development. Conversely, adverse early events in life may have consequences later in life. This review focuses on our understanding of the bacterial microbiome and virome during early development, conditions that might influence these processes, and their long-term implications for infant health.

Antibiotics, obesity and the link to microbes - what are we doing to our children?

BACKGROUND

Childhood obesity and overweight are among the greatest health challenges in the pediatric population. Obese individuals exhibit marked differences in the composition of the intestinal microbial community as compared to lean subjects. These changes in the gut microbiota precede the clinical manifestation of overweight. Convincing experimental data suggest a causal role for intestinal microbes in the development of obesity and associated metabolic disorders.

DISCUSSION

Exposure to antibiotics exerts a devastating impact on the intestinal microbial community. Epidemiological studies have provided evidence indicating that early or repeated childhood exposure to antibiotics is associated with increased risk of overweight later in childhood but the causal role of this exposure in obesity development is not clear. However, data from studies conducted using experimental animal models indicate that antibiotic-induced changes in the gut microbiota influence host metabolism and lead to fat accumulation. The intestinal microbiota perturbation caused by antibiotic exposure in the perinatal period appears to program the host to an obesity-prone metabolic phenotype, which persists after the antibiotics have been discontinued and the gut microbiota has recovered. These observations may have serious implications in the clinical setting, since a substantial number of human infants are subjected to antibiotic treatment through the mother during delivery or directly in the immediate neonatal period. The clinical significance of these exposures remains unknown. Prudent use of antibiotics is paramount not only to reduce the propagation of antibiotic-resistant organisms but also to minimize the potentially detrimental long-term metabolic consequences of early antibiotic exposure. Improved means of reliably detecting neonates with bacterial infection would reduce the need for empirical antibiotic exposure initiated based on nonspecific symptoms and signs or risk factors. Finally, means to support healthy microbial contact in neonates and infants requiring antibiotic treatment are needed.

Planned Repeat Cesarean Section at Term and Adverse Childhood Health Outcomes: A Record-Linkage Study

BACKGROUND

Global cesarean section (CS) rates range from 1% to 52%, with a previous CS being the commonest indication. Labour following a previous CS carries risk of scar rupture, with potential for offspring hypoxic brain injury, leading to high rates of repeat elective CS. However, the effect of delivery by CS on long-term outcomes in children is unclear. Increasing evidence suggests that in avoiding exposure to maternal bowel flora during labour or vaginal birth, offspring delivered by CS may be adversely affected in terms of energy uptake from the gut and immune development, increasing obesity and asthma risks, respectively. This study aimed to address the evidence gap on long-term childhood outcomes following repeat CS by comparing adverse childhood health outcomes after (1) planned repeat CS and (2) unscheduled repeat CS with those that follow vaginal birth after CS (VBAC).

METHODS AND FINDINGS

A data-linkage cohort study was performed. All second-born, term, singleton offspring delivered between 1 January 1993 and 31 December 2007 in Scotland, UK, to women with a history of CS (n = 40,145) were followed up until 31 January 2015. Outcomes assessed included obesity at age 5 y, hospitalisation with asthma, learning disability, cerebral palsy, and death. Cox regression and binary logistic regression were used as appropriate to compare outcomes following planned repeat CS (n = 17,919) and unscheduled repeat CS (n = 8,847) with those following VBAC (n = 13,379). Risk of hospitalisation with asthma was greater following both unscheduled repeat CS (3.7% versus 3.3%, adjusted hazard ratio [HR] 1.18, 95% CI 1.05-1.33) and planned repeat CS (3.6% versus 3.3%, adjusted HR 1.24, 95% CI 1.09-1.42) compared with VBAC. Learning disability and death were more common following unscheduled repeat CS compared with VBAC (3.7% versus 2.3%, adjusted odds ratio 1.64, 95% CI 1.17-2.29, and 0.5% versus 0.4%, adjusted HR 1.50, 95% CI 1.00-2.25, respectively). Risk of obesity at age 5 y and risk of cerebral palsy were similar between planned repeat CS or unscheduled repeat CS and VBAC. Study limitations include the risk that women undergoing an unscheduled CS had intended to have a planned CS, and lack of data on indication for CS, which may confound the findings.

CONCLUSIONS

Birth by repeat CS, whether planned or unscheduled, was associated with an increased risk of hospitalisation with asthma but no difference in risk of obesity at age 5 y. Greater risk of death and learning disability following unscheduled repeat CS compared to VBAC may reflect complications during labour. Further research, including meta-analyses of studies of rarer outcomes (e.g., cerebral palsy), are needed to confirm whether such risks are similar between delivery groups.

The very low birth weight infant microbiome and childhood health

This review describes current understandings about the nature of the very low birth weight infant (VLBW) gut microbiome. VLBW infants often experience disruptive pregnancies and births, and prenatal factors can influence the maturity of the gut and immune system, and disturb microbial balance and succession. Many VLBWs experience rapid vaginal or Caesarean births. After birth these infants often have delays in enteral feeding, and many receive little or no mother's own milk. Furthermore the stressors of neonatal life in the hospital environment, common use of antibiotics, invasive procedures and maternal separation can contribute to dysbiosis. These infants experience gastrointestinal dysfunction, sepsis, transfusions, necrotizing enterocolitis, oxygen toxicity, and other pathophysiological conditions that affect the normal microbiota. The skin is susceptible to dysbiosis, due to its fragility and contact with NICU organisms. Dysbiosis in early life may resolve but little is known about the timing of the development of the signature gut microbiome in VLBWs. Dysbiosis has been associated with a number of physical and behavioral problems, including autism spectrum disorders, allergy and asthma, gastrointestinal disease, obesity, depression, and anxiety. Dysbiosis may be prevented or ameliorated in part by prenatal care, breast milk feeding, skin to skin contact, use of antibiotics only when necessary, and vigilance during infancy and early childhood.

Planned Cesarean Delivery at Term and Adverse Outcomes in Childhood Health

IMPORTANCE

Planned cesarean delivery comprises a significant proportion of births globally, with combined rates of planned and unscheduled cesarean delivery in a number of regions approaching 50%. Observational studies have shown that offspring born by cesarean delivery are at increased risk of ill health in childhood, but these studies have been unable to adjust for some key confounding variables. Additionally, risk of death beyond the neonatal period has not yet been reported for offspring born by planned cesarean delivery.

OBJECTIVE

To investigate the relationship between planned cesarean delivery and offspring health problems or death in childhood.

DESIGN, SETTING, AND PARTICIPANTS

Population-based data-linkage study of 321,287 term singleton first-born offspring born in Scotland, United Kingdom, between 1993 and 2007, with follow-up until February 2015.

EXPOSURES

Offspring born by planned cesarean delivery in a first pregnancy were compared with offspring born by unscheduled cesarean delivery and with offspring delivered vaginally.

MAIN OUTCOMES AND MEASURES

The primary outcome was asthma requiring hospital admission; secondary outcomes were salbutamol inhaler prescription at age 5 years, obesity at age 5 years, inflammatory bowel disease, type 1 diabetes, cancer, and death.

RESULTS

Compared with offspring born by unscheduled cesarean delivery (n = 56,015 [17.4%]), those born by planned cesarean delivery (12,355 [3.8%]) were at no significantly different risk of asthma requiring hospital admission, salbutamol inhaler prescription at age 5 years, obesity at age 5 years, inflammatory bowel disease, cancer, or death but were at increased risk of type 1 diabetes (0.66% vs 0.44%; difference, 0.22% [95% CI, 0.13%-0.31%]; adjusted hazard ratio [HR], 1.35 [95% CI, 1.05-1.75]). In comparison with children born vaginally (n = 252,917 [78.7%]), offspring born by planned cesarean delivery were at increased risk of asthma requiring hospital admission (3.73% vs 3.41%; difference, 0.32% [95% CI, 0.21%-0.42%]; adjusted HR, 1.22 [95% CI, 1.11-1.34]), salbutamol inhaler prescription at age 5 years (10.34% vs 9.62%; difference, 0.72% [95% CI, 0.36%-1.07%]; adjusted HR, 1.13 [95% CI, 1.01-1.26]), and death (0.40% vs 0.32%; difference, 0.08% [95% CI, 0.02%-1.00%]; adjusted HR, 1.41 [95% CI, 1.05-1.90]), whereas there were no significant differences in risk of obesity at age 5 years, inflammatory bowel disease, type 1 diabetes, or cancer.

CONCLUSIONS AND RELEVANCE

Among offspring of women with first births in Scotland between 1993 and 2007, planned cesarean delivery compared with vaginal delivery (but not compared with unscheduled cesarean delivery) was associated with a small absolute increased risk of asthma requiring hospital admission, salbutamol inhaler prescription at age 5 years, and all-cause death by age 21 years. Further investigation is needed to understand whether the observed associations are causal.