C-Sections Cause Childhood Obesity, True or False?

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A few recent studies with weak design sought a link between pediatric obesity and method of delivery: vaginal birth versus cesarean section.

Confirmation bias typically arises from seeking information that confirms your predetermined hypothesis. To simplify: what you seek, you shall find.

So gave birth to the notion that there could be causality or at a minimum a link between Cesarean Delivery (CD) and the development of childhood obesity. The reality is rates for both have been on the rise in recent decades which is why pursuing a magic bullet relationship holds appeal. 

However, a new longitudinal study just published in the journal Pediatrics undermines this belief.

Researchers “examined the development of BMI (body mass index) from birth through childhood to determine whether CDs were associated with differences in growth and obesity.” Using term children from birth cohorts Copenhagen Prospective Studies on Asthma in Childhood (COPSAC 2000 & 2010), the team determined “there were no differences in BMI trajectory…by 5 and 13 years, nor cross-sectional BMI at 5 and 13 years, nor in fat percentages from the DXA (dual-energy x-ray absorptiometry) scans.”

They conclude: “Children delivered by CD had a higher mean BMI at 6 months of age, but this difference did not track into later childhood. Our study does not support the hypothesis that CD leads to later overweight.” Further pertinent findings from their work:

  • The mothers born by CD were older.
  • Children born by CD had a lower gestational age (aka were younger).
  • Children delivered by CD had higher standardized birth weight for gestational age and a shorter duration of exclusive breastfeeding (seen in COPSAC 2010, not 2000).
  • Mothers who delivered by CD (2010 group) had higher prepregnancy BMI and more likely to be nulliparous— a woman who has not given birth.
  • No significant association in BMI or body composition in childhood/puberty and delivery mode—no risk of being overweight in later childhood.

Much of prior scant work on the topic lacked vital details like maternal prepregnancy weight, gestational diabetes status, type of feeding (e.g. breastmilk or formula) etc. Why does that matter? These are essential factors that influence decision-making to section a pregnant mother in the first place and substantially contribute to the weight discussion. 

Maternal history is baby’s history. Without knowledge of mom’s prepregnancy status or baby’s feeding specifics, for example, accurately determining an association between delivery mode and future obesity is wrought with deficiencies.

Since pediatric obesity—and obesity, in general— has a multifactorial, complex etiology, searching for a singular cause makes everyone’s world easier. But, life is a bit more messy and complicated. Genetics, environment, medical history, lifestyle and behavioral facets (among others) play a role. 

Placing this and past studies into context is crucial to understanding the bigger picture. Now we can explore some reasons why an infant born via c-section having a greater BMI in the first 6 months compared to those with vaginal deliveries makes a lot of sense. As does the fact weights evened out so quickly thereafter and throughout childhood. While a few previous studies attempted to determine causality of CD as the inciting event for later childhood obesity, I will underscore why dismissing valuable details impedes such conclusions. 

For example, we know babies born to mothers with gestational diabetes have a higher risk of becoming overweight or developing Type 2 Diabetes. A baby in this scenario, in particular when sub-optimally controlled, will tend to be larger. This macrosomia (aka large body) can pose a challenge to vaginal birth, so is often more likely to be born via CD. Regardless of delivery mode, this infant carries greater risk of being overweight than his contemporary not born under poorly controlled diabetes of pregnancy. 

The CD is not the main culprit here, the history is.

We are speaking of risk stratification, not certainty or guarantee. Fortunately, there are preventive measures that can be quite successful which is why a complete history is so critical.

Hence, knowing this status is vital to interpreting any real or imagined correlation. As is the mechanism of infant feeding. The benefit with formula in teasing out growth is the fact that we know the caloric content of each type due to standardization in manufacturing, so can precisely monitor intake. In terms of the breastfed infant, though volume can be sufficiently maintained by the mother if she is calorie-deficient but well-hydrated the breastmilk will be nutritionally deficient. Knowing its calorie content requires laboratory analysis since it is not the same between individuals. This is an inefficient and often impractical exercise, so following infant growth or lack thereof is the more practical measure. How and what an infant eats tells much of the story.

Additionally, it is typically harder to overfeed a breastfed baby than a formula-fed one. The tendency to placate an infant with feeds is quite common since at this developmental phase the baby cannot verbally convey his needs. Whether a mother breastfeeds or not is a personal decision that can be influenced by a wide range of considerations like medical concerns for her or the newborn to a complicated post-surgical course to individual preference.

Such are some explanations as to why the mean BMI growth diversion in the first 6 months of life.

Whether an infant receives breast milk or formula can often depend on the early period after birth. Since the act of CD especially in a first time mother can delay milk production, early formula supplementation routinely takes place. The body has memory, so for a first-time mom there won’t be this benefit. In the situation of the infant born to a diabetic mother, birth marks an abrupt cessation of higher levels of glucose—or blood sugar—and these babies can have issues with low blood sugar (e.g. hypoglycemia) so require early feeding for therapeutic purposes. Since mom’s milk is not in during this period, formula can be most effective in the newborn with hypoglycemia. 

This is one mere instance where underlying issues prompted the c-section in a population with a higher risk for future obesity. The babies born here are usually heavier. So, remaining so in the first few months especially if formula fed would be expected. 

The first year of life—but especially the first six months —should reflect the most rapid growth rate for babies no matter the mode. In the first six months, the baby takes in calories but doesn’t go to the gym since developmentally they can’t do much physically. They barely work out except during a feed. Around and approaching the six month point, they begin to become more vigorous, sitting up, flailing around, rolling over etc. Because they encounter a personality explosion and are very stimulated by the world around them, they start to take in less breast milk or formula and burn more calories from their enhanced mobility. So, leaning out in the 6-9 month span is common.

So, what’s the real deal about the health risks or benefits of c-sections versus vaginal births? 

The real deal is as nature intended, when possible, is in the best interest of the infant and mother. However, possessing the ability to perform a c-section to ensure the healthiest outcome for mother and child is a true gift of modern medical advancement. Determining which mode is safest for the clinical situation at hand, requires real-time case-by-case assessment. Looking at a medical record after the fact will not do justice to the issue. 

C-section is a medical intervention that should be performed for a medical purpose. It is a significant surgery and the accompanying recovery and challenges vary for mother and baby. I address why Planned Birth For Non-Medical Reasons Not Such A Good Idea here.

There can be differences in the perinatal period for the baby depending upon which avenue is taken. C-sections abort the process of traveling through the birth canal which readies infants for their first breath, so these babies are more prone to transient tachypnea of the newborn which is a mechanical and physiological issue —due to the complexity of the perinatal circulation, for instance. This is routinely addressed and more commonly the babies recover quickly requiring little support. Long-term significance depends on how substantial the lung condition is from that period and what interventions took place. Some might be preterm, for example, where degree of lung immaturity can contribute to problems down the line. 

C-sections can, as previously discussed, delay a mother’s milk production, protract her recovery, impact future pregnancies and bring about issues that accompany a post-operative period, in general. The decision to do so— when there is time to make one— should be informed and convenience not be the presiding motivator.

When it is medically in her and/or the child’s best interest, it is an effective and ideal option that can secure their well-being. Pregnancy designs the most sophisticated suspension system there is that creates a symbiotic relationship where comprehensive understanding must guide delivery choice. 

Mode of delivery does not guarantee future obesity, or at least that is not what the evidence supports today. Focusing on the situations we can control like altering our lifestyles to include a healthier diet and regular exercise will hold greater success in winning the battle against being overweight or obese.


To read about the hazards of water birth, read Just Say No to Water Birth and Water Birth: To Breathe or Not To Breathe?