Compared with babies born vaginally, babies born by cesarean section have a higher risk of adulthood obesity, diabetes, asthma, immunologic diseases, and leukemia. A study just published July 1 in the American Journal of Obstetrics and Gynecology describes one reason why this is true.
The explanation is that the stress of the vaginal delivery process triggers some beneficial changes in the baby’s stem cells. These changes appear to give the vaginally born babies genetic advantages that persist throughout their lives.
The group of researchers from the Karolinska Instituet (Stocklholm) examined the genes in the blood of 64 babies, of which 27 were born vaginally and 33 were born by cesarean section. All the babies were born healthy, and 33 were boys and 27 girls.
The results showed that babies born by cesarean section had a significantly higher amount of what is called “DNA-methylation”. This is not a change in the gene itself (the DNA) of the baby, but a change if the gene is “turned on” or “turned off”.
Previous research has shown that we have many genes within our cells that can be “expressed” (turned on), or not, depending on environmental factors. For example, if someone is a smoker, this could trigger certain genes to be activated (turned on), which speed the development of lung cancer in that person. Or, if someone is a regular exerciser, the exercise could keep certain genes “turned off”, that otherwise might lead to high blood pressure or diabetes.
Whether we develop some disease in our lifetime depends on both our genes and our environment; which includes our health habits, such as diet and exercise. Healthy habits may help keep bad genes turned off (such as those that lead to cancer), and tend to turn on, or activate, beneficial genes.
During vaginal birth, going through the vaginal canal is a stressful experience for the baby, which sends signals to certain genes that they need to be activated or basically “go to work” to help protect the baby’s life. When the baby is born via cesarean section, it’s almost like the baby’s genes can be lazy; they haven’t had the stress that made them activate.
As explained by Dr. Mikael Norman a pediatrician and one of the study authors: “During a vaginal delivery, the fetus is exposed to an increased level of stress, which in a positive way will prepare the unborn baby for life outside the uterus. This activation of the fetus’ defense systems doesn’t occur when a cesarean section is performed.”
As we reported, Brazil unfortunately has the dubious distinction as being the world’s leader in the rate of cesarean births (China was second at 46%, and Brazil at the top with 47%). The World Health Organization (WHO) recommends that a country’s rate of cesarean sections ideally should be no more than 15%.
Many patients (and their doctors) choose cesarean births for convenience and other reasons, but the data show that unless there is a compelling medical reason for the child to be born by cesarean section, the healthiest approach for the mother and the baby (and even when the baby grows up) is the more natural, vaginal delivery.
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