Association Between Mode of Delivery and Risk of Infection in Early Childhood: A Cohort Study

Association between Cesarean section and neurodevelopmental disorders in a Japanese birth cohort: the Japan Environment and Children's Study

BACKGROUND

The long-term effects of a Cesarean section (CS) birth on child neurodevelopment are of increasing interest. In this study, we examined the associations between mode of delivery and presence of neurodevelopmental disorders in toddlers. Moreover, given that the prevalence of several neurodevelopmental disorders such as autism spectrum disorder (ASD) is known to differ by sex, we also investigated these associations separately in male and female toddlers.

METHODS

We investigated 65,701 mother-toddler pairs from the Japan Environment and Children's Study, a nationally representative children's cohort study. To investigate the associations between mode of delivery (CS or vaginal delivery) and neurodevelopmental disorders (motor delay, intellectual disability, and ASD) in 3-year-old toddlers as a whole and stratified by sex, we used logistic regression models to calculate adjusted odds ratios (aORs) with 95% confidence intervals (CIs).

RESULTS

The morbidity of ASD at age 3 years was higher for children delivered by CS than those delivered vaginally (aOR 1.38, 95% CI 1.04-1.83). However, no such difference was evident in the case of motor delay or intellectual disability (aOR 1.33, 95% CI 0.94-1.89; aOR 1.18, 95% CI 0.94-1.49, respectively). In the analysis by sex, CS was not associated with increased risk of any of the neurodevelopmental disorders in males, but it was associated with increased risks of motor delay (aOR 1.88, 95% CI 1.02-3.47) and ASD (aOR 1.82, 95% CI 1.04-3.16) in females.

CONCLUSIONS

This study provides evidence of significant associations between mode of delivery and neurodevelopmental disorders in early childhood. Females may be more sensitive to the effects of CS than males.

Caesarean section and childhood obesity at age 3 years derived from the Japan Environment and Children's Study

Caesarean section (CS) birth is widely reported to be a risk factor for childhood obesity. Although susceptibility to childhood obesity is influenced by race and ethnicity, it is unclear whether this risk of childhood obesity with CS birth also applies in the Japanese population. We investigated the impact of CS birth on obesity at 3 years of age in Japanese children. We obtained data from 60,769 mother-toddler pairs in the Japan Environment and Children's Study, a large-scale birth cohort study. Obesity was determined by body mass index measured at 3 years of age. Analysis revealed that 11,241 toddlers (18.5%) had a CS birth and that 4912 toddlers (8.1%) were obese. The adjusted risk ratio for obesity at 3 years of age when born by CS compared with vaginal delivery, estimated using inverse probability of treatment weighting, was 1.16 (95% confidence interval 1.08-1.25). These results suggest that CS birth modestly increases the risk of obesity at 3 years of age in Japanese children.

Infant Mode of Delivery Shapes the Skin Mycobiome of Prepubescent Children

Characterizing the skin mycobiome is necessary to define its association with the host immune system, particularly in children. In this study, we describe the skin mycobiome on the face, ventral forearm, and calf of 72 prepubescent children (aged 1 to 10 years) and their mothers, based on internal transcribed spacer (ITS) amplicon sequencing. The age and delivery mode at birth are the most influential factors shaping the skin mycobiome. Compared with that of the vaginally born children, the skin mycobiome of caesarean-born children is assembled by predominantly deterministic niche-based processes and exhibits a more fragile microbial network at all three sampling sites. Moreover, vaginal delivery leads to clearer intra- and interindividual specialization of fungal structures with increasing age; this phenomenon is not observed in caesarean-born children. The maternal correlation with children also differs based on the mode of delivery; specifically, the mycobiomes of vaginally born children at younger ages are more strongly correlated with vagina-associated fungal genera (Candida and Rhodotorula), whereas those of caesarean-delivered children at elder age include more skin-associated and airborne fungal genera (Malassezia and Alternaria). Based on this ecological framework, our results suggest that the delivery mode is significantly associated with maturation of the skin fungal community in children. IMPORTANCE Human skin is permanently colonized by microbes starting at birth. The hygiene hypothesis suggests that a lack of early-life immune imprinting weakens the body's resilience against atopic disorders later in life. To better understand fungal colonization following early-life periods affected by interruption, we studied the skin mycobiomes of 73 children and their mothers. Our results suggest a differentiation of the skin mycobiomes between caesarean-born and vaginally born children. Caesarean-born children exhibit a mycobiome structure with more fitted deterministic niche-based processes, a fragile network, and an unchanged microbial dissimilarity over time. In vaginally born children, this dissimilarity increases with age. The results indicate that initial microbial colonization has a long-term impact on a child's skin mycobiome. We believe that these findings will inspire further investigations of the "hygiene hypothesis" in the human microbiome, especially in providing novel insights into influences on the development of the early-life microbiome.

Beneficial Effects of Limosilactobacillus fermentum CECT 5716 Administration to Infants Delivered by Cesarean Section

Cesarean section (CS) disrupts the natural microbiota colonization process in infants, which might compromise immune system maturation, leading to a higher risk of infections. We evaluated the effect of the probiotic Limosilactobacillus (L.) fermentum CECT 5716 on the incidence of gastrointestinal and respiratory infections in the CS infant subgroups (n = 173) of three randomized clinical trials in which this probiotic strain was demonstrated to be safe and effective for preventing infections. Therefore, the data for the CS infants were extracted to obtain the incidence rate ratio (IRR) and 95% CI for gastrointestinal and respiratory infections for each study and were then combined to obtain a pooled IRR and 95% CI using the generic inverse variance method. There was a significant reduction of 73% in the incidence of gastrointestinal infections in CS infants receiving L. fermentum CECT 5716 compared with those receiving the control formula [n = 173, IRR: 0.27 (0.13, 0.53), p = 0.0002]. Regarding respiratory infections, although pooled results showed a reduction of 14% in the probiotic group, the difference was not statistically significant [n = 173, IRR (95% CI): 0.86 (0.67, 1.11), p = 0.25]. In conclusion, the administration of L. fermentum CECT 5716 to CS-born infants protects them from gastrointestinal infections by reducing the risk by up to 73% in this population.

Age- and sex-specific prevalence of serious bacterial infections in febrile infants ≤60 days, in Sweden

AIM

The aim of the study was to describe age- and sex-specific prevalence of serious bacterial infections (SBI: urinary tract infection, bacteraemia, meningitis) among febrile infants ≤60 days in Sweden.

METHODS

This is a retrospective study in 4 Pediatric Emergency Departments from 2014 to 2017, in previously healthy, full-term infants ≤60 days with fever without a source.

RESULTS

Of the 1,701 included infants, 214 (12.6%; 95% CI, 11.1-14.3) had an SBI. Urinary tract infection (UTI) was diagnosed in 196 (11.5%; 95% CI, 10.0-13.1) patients. In the ≤28 and 29-60 days age-groups, meningitis prevalence was 0.9% (95% CI, 0.3-2.0) and 0.3% (95% CI, 0.1-0.8), whereas bacteraemia prevalence was 3.2% (95% CI, 1.9-4.9) and 0.6% (95% CI, 0.2-1.3). The SBI prevalence was higher in boys 16.0% (95% CI, 13.8-18.5) than girls 8.0% (95% CI, 6.2-10.2; p<0.001), due to 2-fold higher UTI risk. The prevalence of meningitis in boys was 0.3% (95% CI, 0.1- 0.9) vs. 0.7% (95% CI, 0.2-1.6) in girls and of bacteraemia 1.8% (95% CI, 1.0-2.8) vs. 1.0% (95% CI, 0.4-2.0), respectively.

CONCLUSIONS

The total SBI prevalence was 12.6%, and UTI represented the vast majority. The prevalence of bacteraemia and meningitis was low, particularly in the 29-60 days age group, without significant difference between boys and girls.

Association of Cesarean Delivery with Childhood Hospitalization for Infections Before 13 Years of Age

OBJECTIVES

To determine the association between cesarean delivery and childhood infections up to 13 years of age.

STUDY DESIGN

We conducted a longitudinal cohort study of 731 803 children born between 2006 and 2016 at all hospitals in the province of Quebec, Canada. We followed children born by cesarean, operative vaginal, and nonoperative vaginal delivery up to 13 years of age. Outcomes included hospitalization for otitis media, respiratory, infectious enteritis, and other infections. We estimated hazard ratios with 95% CIs for the association between mode of delivery and childhood infections, adjusted for patient characteristics.

RESULTS

At age 3-4 years, cesarean delivery was associated with a 1.07-fold greater risk of otitis media (95% CI, 1.03-1.11), a 1.15-fold greater risk of respiratory infection (95% CI, 1.09-1.22), and a 1.13-fold greater risk of infectious enteritis (95% CI, 1.03-1.25) compared with nonoperative vaginal delivery. However, operative vaginal delivery was associated with these same outcomes. Both cesarean and operative vaginal delivery were more strongly associated with infection hospitalization before age 1 year, but associations disappeared after 5 years.

CONCLUSIONS

Cesarean delivery is associated with infection hospitalization before but not after age 5 years. However, associations were also present for operative vaginal delivery, which suggests that mechanisms other than exposure to maternal vaginal flora explain the relationship.

Exposure to perfluoroalkyl substances during fetal life and hospitalization for infectious disease in childhood: A study among 1,503 children from the Odense Child Cohort

INTRODUCTION

The immunosuppressive properties of PFASs are widely recognized. Early-life exposure to PFAS has been linked to reduced immune response to childhood vaccinations and increased rates of common infectious diseases, but implications for hospitalizations are unclear.

OBJECTIVES

To investigate the association between maternal serum concentrations of five PFASs during pregnancy and the child's rate of hospitalization due to common infectious diseases between birth and 4 years of age.

METHODS

Serum samples from first trimester pregnant women from the Odense Child Cohort (OCC) collected in 2010-2012 were analyzed for concentrations of perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and three other PFASs. Data on child hospitalizations with an ICD-10 code for infectious disease was obtained from the Danish National Patient Register. The following were identified: upper respiratory tract infections (URTI), lower respiratory tract infections (LRTI), gastrointestinal infections (GI), and other infections. The Andersen-Gill Cox proportional hazard model for recurrent events was used to investigate the association between PFAS exposure and hospitalizations. The resulting estimates were hazard ratios (HRs), which express the relative change in the instantaneous risk of hospitalization with a doubling in maternal PFAS concentration.

RESULTS

A total of 1,503 mother-child pairs were included, and 26% of the children were hospitalized at least once for infectious disease. A doubling in maternal PFOS concentration was associated with a 23% increase in the risk of hospitalization due to any infection (HR: 1.23 (95% CI: 1.05, 1.44). There was indication of an interaction between child sex and PFOS (p = 0.07) and PFDA (p = 0.06), although in opposite directions. Further, every doubling of PFOA or PFOS increased the risk of LRTI by 27% (HR: 1.27 (1.01, 1.59)) and 54% (HR: 1.54 (1.11, 2.15)), respectively. Similar tendencies were seen for URTI and the group of other infections. For GIs, the opposite pattern of association was seen as HR's were consistently below 1 (PFOA, HR: 0.55 (0.32, 0.95)).

DISCUSSION

We found an association between PFOS and the overall risk of infectious disease, and between PFOS and PFOA exposures and the risk of LRTI's. These results are in agreement with previous findings from the OCC, in which maternal PFOS and PFOA concentrations were positively associated with the number of days that the children experienced fever, thereby suggesting that PFOS and PFOA may affect the prevalence of both mild and more severe infectious diseases even in a rather low-exposed population.

Delivery Modality Affect Neonatal Levels of Inflammation, Stress, and Growth Factors

Introduction: As part of the study CODIBINE, Correlations and Diagnoses for Biomarkers in New-borns, the main objective of the study was to explore neonatal inflammation, stress, neurodevelopment, and growth factors after in-labor and pre-labor cesarean section compared to vaginal delivery. Increasing evidence has shown that birth delivery mode has an impact on imminent and long-term child health. However, the effect of the timing of cesarean section is insufficiently elucidated. The main objective of the study was to explore the effect of different delivery modes, vaginal delivery compared to cesarean section with or without initiation of labor, on the infants. Methods: We designed a retrospective cohort study, including dried blood spot samples from mature (gestational age ≥ 37) newborns delivered in the years 2009-2011. The newborns were divided into three groups after delivery mode: (1) pre-labor cesarean section (n = 714), i.e., cesarean delivery without initiation of labor, (2) in-labor cesarean section (n = 655), i.e., cesarean section after initiation of labor, and (3) vaginal delivery (n = 5,897). We measured infant levels of inflammatory (IL-18, MCP-1, CRP, sTNF RI), stress (HSP-70), growth (EGF, VEGF-A), and neurotrophic factors (BDNF, NT-3, S100B) 2-4 days after birth. Results: The neonatal levels of inflammatory and stress markers were significantly lower, while the levels of growth factors were higher after pre-labor cesarean section compared to vaginal delivery. The biomarker levels were similar after in-labor cesarean section and vaginal delivery. Removing cases with pre-labor rupture of membranes and artificial rupture of membranes in the calculations did not change the results. The levels of neurotrophic factors were unaffected by delivery form. Males had generally higher levels of inflammation and lower levels of growth and neurotrophic factors. Overall, the levels of inflammatory markers increased, and the growth factors decreased with increasing gestational age. Conclusion: The present study of the biomarker levels after birth suggests that the labor process has an important effect on the fetal immune system and level of stress, regardless if the delivery ends with cesarean section or vaginal birth.

Changing Epidemiology of Acute Respiratory Infections in Under-Two Children in Dhaka, Bangladesh

Objectives: Risk factors for acute respiratory infections (ARIs) in community settings are not fully understood, especially in low-income countries. We examined the incidence and risk factors associated with ARIs in under-two children from the Microbiota and Health study. Methods: Children from a peri-urban area of Dhaka (Bangladesh) were followed from birth to 2 years of age by both active surveillance of ARIs and regular scheduled visits. Nasopharyngeal samples were collected during scheduled visits for detection of bacterial facultative respiratory pathogens. Information on socioeconomic, environmental, and household conditions, and mother and child characteristics were collected. A hierarchical modeling approach was used to identify proximate determinants of ARIs. Results: Of 267 infants, 87.3% experienced at least one ARI episode during the first 2 years of life. The peak incidence of ARIs was 330 infections per 100 infant-years and occurred between 2 and 4 months of age. Season was the main risk factor (rainy monsoon season, incidence rate ratio [IRR] 2.43 [1.92-3.07]; cool dry winter, IRR 2.10 [1.65-2.67] compared with hot dry summer) in the first 2 years of life. In addition, during the first 6 months of life, young maternal age (<22 years; IRR 1.34 [1.01-1.77]) and low birth weight (<2,500 g; IRR 1.39 [1.03-1.89]) were associated with higher ARI incidence. Conclusions: Reminiscent of industrialized settings, cool rainy season rather than socioeconomic and hygiene conditions was a major risk factor for ARIs in peri-urban Bangladesh. Understanding the causal links between seasonally variable factors such as temperature, humidity, crowding, diet, and ARIs will inform prevention measures.

Breastfeeding and Infections in Early Childhood: A Cohort Study

BACKGROUND

Studies on the association between breastfeeding and infections in children beyond the first year of life reveal conflicting results. In a population-based birth cohort, we investigated whether the duration of breastfeeding was associated with the number of hospitalizations due to infection and symptoms of infection at home.

METHODS

In the Odense Child Cohort, text message questionnaires were used to register information on breastfeeding (weekly until end of weaning) and symptoms of infection (biweekly; 12-36 months of age). Hospitalization data were obtained from the Danish National Patient Registry.

RESULTS

Of the 1087 invited, 815 mother-infant pairs were included. The median duration of any breastfeeding was 7.6 (interquartile range: 3.5-10.4) months and of exclusive breastfeeding was 2.1 (interquartile range: 0.7-4.4) months. Hospitalization due to infection was seen in 207 (25.4%) infants during the first 3 years of life. The adjusted incidence rate ratio (IRR) for hospitalization due to any infection decreased with a longer duration of any breastfeeding (adjusted IRR: 0.96; 95% confidence interval 0.93-0.99; P < .001). The strongest associations between the duration of any breastfeeding and hospitalizations due to infection were found within the first year of life, for lower respiratory tract infections, and other infections (P ≤ .05). For infants exclusively breastfed, the adjusted IRR for hospitalization was 0.88 (95% confidence interval: 0.80-0.96; P = .006). No protective associations were present between breastfeeding and infection symptoms registered at home from ages 12 to 36 months.

CONCLUSIONS

The results suggest that increased duration of breastfeeding, especially exclusive breastfeeding, protects against infections requiring hospitalization in the first year of life but not hospitalizations or symptoms of infection at home beyond the first year.

Mode of birth and risk of infection-related hospitalisation in childhood: A population cohort study of 7.17 million births from 4 high-income countries

BACKGROUND

The proportion of births via cesarean section (CS) varies worldwide and in many countries exceeds WHO-recommended rates. Long-term health outcomes for children born by CS are poorly understood, but limited data suggest that CS is associated with increased infection-related hospitalisation. We investigated the relationship between mode of birth and childhood infection-related hospitalisation in high-income countries with varying CS rates.

METHODS AND FINDINGS

We conducted a multicountry population-based cohort study of all recorded singleton live births from January 1, 1996 to December 31, 2015 using record-linked birth and hospitalisation data from Denmark, Scotland, England, and Australia (New South Wales and Western Australia). Birth years within the date range varied by site, but data were available from at least 2001 to 2010 for each site. Mode of birth was categorised as vaginal or CS (emergency/elective). Infection-related hospitalisations (overall and by clinical type) occurring after the birth-related discharge date were identified in children until 5 years of age by primary/secondary International Classification of Diseases, 10th Revision (ICD-10) diagnosis codes. Analysis used Cox regression models, adjusting for maternal factors, birth parameters, and socioeconomic status, with results pooled using meta-analysis. In total, 7,174,787 live recorded births were included. Of these, 1,681,966 (23%, range by jurisdiction 17%-29%) were by CS, of which 727,755 (43%, range 38%-57%) were elective. A total of 1,502,537 offspring (21%) had at least 1 infection-related hospitalisation. Compared to vaginally born children, risk of infection was greater among CS-born children (hazard ratio (HR) from random effects model, HR 1.10, 95% confidence interval (CI) 1.09-1.12, p < 0.001). The risk was higher following both elective (HR 1.13, 95% CI 1.12-1.13, p < 0.001) and emergency CS (HR 1.09, 95% CI 1.06-1.12, p < 0.001). Increased risks persisted to 5 years and were highest for respiratory, gastrointestinal, and viral infections. Findings were comparable in prespecified subanalyses of children born to mothers at low obstetric risk and unchanged in sensitivity analyses. Limitations include site-specific and longitudinal variations in clinical practice and in the definition and availability of some data. Data on postnatal factors were not available.

CONCLUSIONS

In this study, we observed a consistent association between birth by CS and infection-related hospitalisation in early childhood. Notwithstanding the limitations of observational data, the associations may reflect differences in early microbial exposure by mode of birth, which should be investigated by mechanistic studies. If our findings are confirmed, they could inform efforts to reduce elective CS rates that are not clinically indicated.

Delivery mode and future infectious morbidity of the offspring: a sibling analysis

PURPOSE

Cesarean delivery (CD) has been recently suggested to be associated with offspring's long-term health implications. We aimed to investigate the association between delivery mode and long-term infectious morbidity of the offspring while employing sibling matched analysis to maximize confounder control.

METHODS

A retrospective population-based cohort study was performed, which included all sibling deliveries occurring between 1991 and 2014 at a regional tertiary medical center. Offsprings were followed up until the age of 18 years. The study included 13,516 individuals (6758 sibling pairs): the first born was via vaginal delivery and the second via CD. Each siblings pair was considered a matched set, with the aim to perform a within-family analysis. A Kaplan-Meier survival curve was used to compare the cumulative infectious morbidity incidence and a multivariable Cox survival hazards regression model to control for confounders.

RESULTS

Crude rates of total infectious hospitalizations were found to be significantly higher in the CD group (OR 1.25; 95% CI 1.12-1.40). Specifically, bronchiolitis (OR 2.02, 95% CI 1.56-2.63), otitis (OR 1.52, 95% CI 1.21-1.9), and gastroenteritis (OR 1.41, 95% CI 1.05-1.9) were all found to be significantly more common in the CD group. The survival curve demonstrated significantly higher cumulative infection-related hospitalization rates in the CD group (log-rank p < 0.001). The Cox model, adjusted for several confounders, confirmed the significant association between CD and offspring's infection-related morbidity (adjusted HR 1.25; 95% CI 1.02-1.53).

CONCLUSION

CD appears to be independently associated with later offspring infection-related morbidity, even while rigorously adjusting for confounders.

Birth Season and Infection Risk Among Children Under 5 Years Old: A Study of Hospital Admissions and Short Message Service-reported Symptoms at Home

BACKGROUND

The season in which a child is born may affect the immune system development and thereby influence the risk of infections. In this study, we examined the associations between birth season and the risk of hospital admission or symptoms associated with a wide range of infections.

METHODS

This study is a prospective cohort study of 2434 children with an average follow-up of 3.5 years. Admission data were obtained from the Danish National Patient Registry. Via short message service (SMS) questionnaires, 1279 families reported symptoms of infections in a 1-year period.

RESULTS

Of the 2434 children, 639 (26.3%) were admitted to the hospital, and the children experienced on average 64.4 days with symptoms of infection within 1 year. There was no association between birth season and hospital admissions due to all infectious causes [incidence rate ratio (IRR) = 0.89; 95% confidence interval (CI), 0.65-1.22; P = 0.471]. However, children born in the fall had a higher IRR for admission due to all infectious causes when excluding admissions within the first year of life. Winter- and spring-born children had lower IRRs for admission due to gastrointestinal infections than summer-born children, but this association was alone present when admissions within the first year of life were included. The short message service-survey showed significantly lower IRRs for any symptom of infection among winter-born (IRR = 0.85; 95% CI, 0.75-0.96; P = 0.009) and fall-born children (IRR = 0.88; 95% CI, 0.78-0.99; P = 0.033) in comparison with summer-born children.

CONCLUSIONS

Birth season was not associated with hospital admission due to all infectious causes within the first 5 years of age; however, fall-birth was associated with a higher IRR for admissions due to all infectious causes after the first year of life. The association between birth season and admissions due to gastrointestinal infections was only seen when including children admitted under the age of one. Being born in fall or winter was associated with a decreased IRR for number of days with any symptom of infection registered at home.