Caesarean births linked to higher childhood obesity risk, Japanese study finds

A recent scientific study published in the journal Scientific Reports explores the potential impact of Caesarean section (CS) delivery on the incidence of obesity among three-year-old Japanese children.

Childhood obesity is a growing global health issue, as it can often persist into adulthood and raise the risk of various cardiometabolic disorders. Prior research has suggested that children born via CS may have a higher likelihood of obesity, potentially due to disturbances in their gut microbiomes. These children have been found to exhibit lower adiponectin levels and greater insulin resistance.

While ethnicity and race are also factors in the prevalence of paediatric obesity, with Asian children reportedly at a higher risk than their White and European counterparts, the correlation between CS birth and childhood obesity in the Japanese population remains relatively unexplored.

The objective of this study was to investigate this correlation, which could aid in the early identification of children at risk of adult obesity, thereby enabling early intervention through weight management programs.

For the study, the research team analysed data from 60,769 Japanese mother-child pairs participating in the national Japan Environment and Children’s Study (JECS). The mode of delivery was determined from health records, while anthropometric data was gathered through online questionnaires completed by the participants themselves.

The researchers identified obesity in children using the body mass index (BMI) cut-off values defined by the International Obesity Task Force guidelines, and only included children from singleton births in the analysis. The study excluded any multiple participations, multiple births, stillbirths or miscarriages, or any data with missing information related to height and/or weight, mode of delivery, and other covariates.

The researchers used logistic regression analysis and estimated adjusted risk ratios (aRR), taking into account various maternal and paediatric factors. They also conducted a sensitivity analysis using the obesity thresholds provided by the Japanese Association for Human Auxology guidelines.

The study found that 19% of the children were born via CS, with 8% classified as having obesity. The aRR for obesity in three-year-old Japanese children born through CS was 1.2 compared to those born via vaginal delivery. When the data was stratified by sex, the aRR values were 1.1 for boys and 1.2 for girls.

The sensitivity analysis corroborated these findings, with the risk of childhood obesity remaining statistically significant for Japanese girls. This aligns with previous studies that have reported an increased risk of certain cancers in females born through CS.

The data also revealed that children born via CS had lower birth weights and heights and were more likely to be born before 37 weeks of gestation. Mothers who had a CS were generally older, had higher pre-pregnancy BMIs, were less educated, and had a higher rate of pregnancy-related and obstetric complications. They were also more likely to smoke, suffer from physical illnesses, and use assisted reproductive technology.

In conclusion, the study suggests that CS births slightly heighten the risk of obesity at age three for both boys and girls in the Japanese population. This indicates that the mode of delivery may influence metabolic health, even among ethnic groups that are typically less prone to obesity. Factors such as maternal pre-pregnancy BMI, education level, and the child’s birth weight appeared to confound this relationship.

The study emphasises the need for further research to understand the mechanisms underlying the increased risk of paediatric obesity associated with CS delivery, including the possible association with gut microbiota. Moreover, the long-term cardiometabolic impacts of CS delivery should be further investigated.