C-section delivery, a rarity in older days has become very common now. Call it a delivery of convenience to overpower nature by bringing in the newborn into this world at an auspicious time fixed by us or as a result of lifestyle changes that hamper the natural delivery mode that leads to failure in labour pain, correct positioning/fixation of the baby’s head and so on. Whatever it is, caesarean rates have spiked up from 6.7% in 1990 to 19.1% in 2014. Various reasons quoted for such increase in rates include advanced maternal age at childbirth, physician fear of litigation, decrease in vaginal births after C-section and access to private health insurance.
Gut microbiota shapes an individual’s health and babies born through C-section delivery are not exposed to the mom’s vagina as compared to babies born through natural delivery-initial microbiota of the fetus depends on the bacteria composition transferred from the mom to the child via her birth canal. Gut microbiome of c-section babies is not diverse and we have studies showing that their gut microbiome might harvest more dietary nutrients predisposing them to be obese/overweight. There have been numerous theories suggesting that kids born through C-section deliveries face higher risk of being obese/overweight compared to kids born through natural birth. Lets look at various studies that tried to find out the real link between mode of delivery and risk of overweight/obesity.
Evidence from Cohort Study
Detailed here is the growing up in Ireland (GUI) study that recruited 11,134 infants born in Ireland born between Dec 2007 and June 2008. When the infants were 9-months old all the families participated in a face-to-face questionnaire session conducted by trained interviewers. When the child was 3- and 5-years old all the mother-infant pairs followed up with home-based interview sessions. But after imposing various exclusion criteria the research team was left with 11,049 infant-mother pairs at baseline. Even those infants born through vaginal breech delivery were excluded from the study.
Delivery mode was split into four categories namely vaginal delivery (VD), assisted VD, elective/planned caesarean section (CS) and emergency/unplanned CS. Moms who opted for the last two options were either in pre-labour or in labour respectively. The time of labour contractions is important as the offspring’s microbial colonisation begins later. For instance, children born by pre-labour CS have no exposure to vaginal microflora whereas kids born through CS in labour comparatively have an advantageous edge as they are likelier to be exposed to the mom’s microbiome. Each of the child’s height, weight and BMI measurements were taken and they were all classified as thin, normal & overweight/obese depending on the values procured. Breastfeeding practice was also considered as mothers who opted for elective CS were unlikelier to breastfeed and its known that babies who don’t breastfeed are at a higher risk of obesity.
8,175 of the 11,049 infants were delivered vaginally-almost 60% was by normal VD and the rest was by assisted VD. 26% of the deliveries were by CS-12.7% by elective CS and 13.3% by emergency CS. 51.1% of the participants were boys and almost 55% of deliveries were by assisted VD and emergency CS. Among women who opted for elective CS almost 50.4% of them 35 years and above. After birth it was observed that 13.9% kids were macrosomic (more than 4 kilograms), 10.9% were large for gestational age; at the age of 3, 1,767 (18.7%) of them were overweight and 506 (5.3%) were obese and at the age of five, 1389 (15.8%) of them were overweight and 437 (5%) were obese. While 5030 (57%) children were within normal BMI ranges between 3 and 5 years of age 175 (2%) were obese. Almost 3% kids who were obese at age 3 became non-obese at age five while 3% who were not obese at age 3 became obese at age 5. 13.2% mothers who delivered vaginally and 21.5% who delivered by CS were obese.
At 3 years: Results showed that a clear link between elective CS and obesity risk could be found at age 3 compared to those kids delivered vaginally (normal). Overweight risk was linked to emergency CS and not elective CS. Elective CS was not linked to obesity risk at age 3 among appropriate for gestational age (AGA) infants. Small for gestational age (SGA) infants had a median birth weight of 3 kilogram and there was a link between emergency CS and obesity in AGA non-macrosomic kids.
At 5 years: There was a slight link between elective CS and obesity risk when the children were five years old and a similar link was seen between emergency CS and obesity risk as well.
Between age 3 and 5: Here, no association was found between elective CS and any BMI category transition. Kids born through emergency CS were at an increased risk of remaining obese between 3 and 5 years of age while those born through emergency CS were at an increased risk of making any other BMI transition.
This study doesn’t clearly prove that there is a causal relationship between elective CS and childhood obesity. An increased risk of obesity in kids born through emergency CS and not elective suggests that there is no causal effect due to vaginal microflora.
Obesity Risk in Preschool Kids in China
C-section delivery in some Chinese cities exceed 50% and generally too, rates of birth by CS has increased from 18% in 1992 to 40% in 2000. At the same time, overweight/obesity rates of kids also have increased from 12.6% in 1997 to 22.1% in 2009. A group of researchers set forth to analyse the effect of CS delivery and risk of childhood obesity in a large sample of preschool kids. 9103 kids aged 3-6 years from 35 different playschools in 5 different kids were included whose parents were given a questionnaire. It was observed that 8900 of 9103 were valid and hence, weight and height information of all these children were collected. WHO guidelines were taken for branding a kid to be overweight (BMI between 85th and 95th percentile) or obese (BMI ≥95th percentile). Delivery mode was also noted down classifying the child into one of the following categories-vaginal delivery and CS (elective/non-elective).
Information on the mother’s age, education, smoking and drinking status, pre-pregnancy weight, maternal weight, breastfeeding status and the child’s birthweight and sex were noted. Maternal pre-pregnancy BMI was calculated based on maternal height and pre-pregnancy weight and paternal BMI was also calculated based on weight and height values.
67.3% kids were born via C-section delivery. It was moms who delivered after the age of 36, who were obese/overweight before pregnancy and with a higher education level (who gained more weight during pregnancy) who were at a higher risk of CS delivery. Of the total kids, 939 kids who were delivered through CS were obese and around 25% kids were not breastfed. Of the 5992 CS deliveries, 4016 (67%) were bon-elective and 1977 (33%) were elective. Of notable interest is the fact that paternal age, BMI and smoking status affected the delivery mode. CS delivery increased the risk of overweight/obesity in kids, both elective and non-elective types.
Longitudinal Cohort Study: Ireland
A longitudinal birth cohort with phenotyping of mom and infant was used to probe into the exact association between CS delivery, prelabour CS and childhood body composition and growth. Data for the study was fetched from the Screening for Pregnancy Endpoints (SCOPE) study and its follow-up prospective Irish birth cohort, the babies after SCOPE (BASELINE) study.
Participants from the BASELINE study were recruited around their 15th week of pregnancy in which 1774 gave their written informed consent and 1537 of them had infants recruited into the BASELINE study. The researchers segregated mode of delivery into four different categories namely unassisted vaginal delivery (VD), operative VD, prelabour lowest segment (LS) CS and LSCS in labour. Operative VD included the use of either forceps or vacuum for delivery. Whole body density, height and weight measurements for each infant were calculated and the kid was classified as either thin, normal, overweight or obese depending on BMI values.
Of the 1305 infants 943 of them were delivered vaginally while the rest were delivered by CS: prelabour LSCS (12%) and LSCS in labour (15.8%). 13% of infants were macrosomic at birth and 11% were large for gestational age. At 2 years of age, 116 (10.9%) kids were overweight/obese and at the age of 5, the number increased to 118. Around 6 months the mean BMI of infants delivered vaginally and by CS was 17.3 and 17.6.
When infants were 2 months old there was no link between prelabour CS and body fat percentage (BF%) and LSCS in labour when compared to kids delivered through unassisted VD. Infants delivered through CS had higher BMI at six months of age compared to those born vaginally. But there was no link between prelabour CS or LSCS in labour and risk of being overweight/obese at age 2. When the kid was 5 years old, there was a nonsignificant link between prelabour CS and the risk of being overweight/obese. There is no clear evidence to support the link between prelabour CS and offspring being overweight/obese in early childhood.
No Link between Mode of Delivery & Overweight Risk
A research team was interested in the long-term effect of CS delivery on offspring health as CS delivery rates are presently higher than ever. They compared the BMI of almost 1,00,000 male individuals who were 18 years and divided them into three categories based on their mode of delivery-vaginally, elective C-section or non-elective C-section. Results showed that 5.5% and 5.6% of participants delivered through elective and non-elective C-section were obese compared to 4.9% of men delivered vaginally. The researchers commented that the mom’s weight before pregnancy had a greater impact on inheriting obesity or affecting foetal health in comparison to which mode of delivery played a negligible role in determining obesity/overweight risk. Researchers could observe that mode of delivery did not play a strong role in impacting obesity risk of offspring even after accounting for various factors such as BMI, maternal age, gestational age and presence of diabetes, BP and smoking in the mothers.
Mothers should be more concerned about their pre-pregnancy weight and health, take good care of themselves during the pregnancy tenure and focus on delivering a healthy baby rather than worrying about the mode of delivery.
The Impact of Caesarean Section on the Risk of Childhood Overweight & Obesity: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6181954/pdf/41598_2018_Article_33482.pdf
Caesarean Section May Increase the Risk of Both Overweight & Obesity in Preschool Children: https://bmcpregnancychildbirth.biomedcentral.com/articles/10.1186/s12884-016-1131-5
Association between Caeserean Section Delivery and Obesity in Childhood: https://bmjopen.bmj.com/content/9/3/e025051
Study Debunks Notion that C-section Would Increase Risk of Obesity in the Child: https://www.sciencedaily.com/releases/2019/12/191206152948.htm
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