Japanese study finds Cesarean births increase childhood obesity risk

By Pooja Toshniwal PahariaReviewed by Benedette Cuffari, M.Sc.Apr 25 2023

In a recent study published in the journal Scientific Reports, researchers examine the influence of Cesarean section (CS) delivery on pediatric obesity among three-year-old Japanese residents.

Study: Caesarean section and childhood obesity at age 3 years derived from the Japan Environment and Children’s Study. Image Credit: Natthawon Chaosakun / Shutterstock.com

Background

Pediatric obesity has concerned health authorities, as obesity during childhood can continue to manifest in adults and elevate cardiometabolic morbidity risks. CS-born adolescents exhibit low adiponectin levels and enhanced resistance to insulin. Moreover, previous studies have reported that CS delivery increases the risk of pediatric obesity, which is likely due to intestinal microbiome dysbiosis.

Ethnicity and race are other factors associated with pediatric obesity, with Asians more likely to have obese children than Whites and Europeans. However, data on the association between Cesarean section birth and pediatric obesity among Japanese children are limited.

Investigating the relationship between CS delivery and pediatric obesity could aid in identifying children at high risk of adulthood obesity to be prioritized in weight management programs.

About the study

In the present study, researchers investigate whether CS delivery could increase obesity risks among Japanese children.

Data were obtained from 60,769 mother-child pairs who participated in the national Japan Environment and Children’s Study (JECS). Data on delivery modes were retrieved from health record transcripts, which were provided by nurses/midwives, physicians, and/or health research coordinators. Anthropometric data were self-documented by the participants in online questionnaires.

The team determined obesity among three-year-olds using body mass index (BMI) cut-off values listed in the International Obesity Task Force guidelines. Only singleton children were included in the final dataset analysis.

Exclusion criteria included multiple participations, multiple births, stillbirths or miscarriages, and missing data concerning height and/or weight, delivery modes, and covariates.

Logistic regression analysis was performed and adjusted risk ratios (aRR) were estimated using inverse probability of treatment weighting adjusting for covariates such as maternal age at pregnancy, BMI before pregnancy, level of education, smoking habits, annual income, alcohol intake, obstetric complications, pregnancy-associated complications, prior physical disease history, and assisted reproductive technology use.

Pediatric covariates included the child’s gender, gestational age, height, and weight at birth. In addition, a sensitivity analysis was performed using obesity thresholds of 16.87 and 17 for males and females, respectively, using the Japanese Association for Human Auxology guidelines.

Study findings

Among the study participants, 19% of children had CS births, and 8% were considered obese. An aRR value of 1.2 was observed for obesity at the age of three years among Japanese children born by CS delivery as compared to those born vaginally. Stratifying by sex, aRR values of 1.1 and 1.2 were observed for male and female children, respectively.

The sensitivity analysis yielded similar findings; however, the risk of pediatric obesity continued to be statistically significant for Japanese girls. This is concordant with previous studies reporting an elevated risk of hepatoblastoma and acute lymphoblastic leukemia after CS birth among females.

The percentages of births before 37 weeks among children delivered through the vaginal and CS routes were 3% and 10%, respectively.

CS-delivered children had lower heights and weights at birth. The maternal proportions over 35 years of age in the vaginal and CS birth groups were 26% and 39%, respectively.

The percentages of mothers with BMI values exceeding 25 during pregnancy in the corresponding groups were 16% and 8.4%, respectively. Mothers with CS deliveries were less educated and had more pregnancy-associated and obstetric complications. In addition, CS group mothers were more likely to smoke, suffer from physical diseases, and use assisted reproductive technology.

Conclusions

CS births modestly increased the risk of obesity at the age of three for both sexes among Japanese individuals. Thus, the mode of delivery appears to affect metabolic physiology, even among ethnicities that are less prone to obesity. Pre-pregnancy BMI values, maternal educational level, and the birth weight of the offspring confounded the association.

Further research is needed to elucidate the mechanisms underlying the increase in the risk of pediatric obesity by CS delivery, including the association between the mode of delivery and the intestinal microbiota. The long-term cardiometabolic implications of CS delivery must also be identified.