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Vaginal Delivery Induces “Good” Stress

A little more than a year ago, my son was born. And, just as the birth of my daughter had been, the delivery became an emergency caesarean section. Neither my first nor my second went all the way, despite hours even days of pain and contractions.

Why am I telling you this? Yes, believe it or not, but the stress induced by giving birth vaginally actually equivalates to a positive impact. At least for the child anyways.

Five years ago, my colleagues did an attention-grabbing study in which they looked epigenetically at how children are affected by vaginal birth compared to being born via caesarean section. This in light of previous studies that have shown that children born via a planned cesarean section have a higher risk of developing asthma, type 1 diabetes, obesity and gluten intolerance later in life. The reason for the connection is not fully established, but as planned caesarean deliveries have increased in many parts of the world, it is of increasing importance to look into this more closely.

In my study, my colleagues investigated epigenetic changes in stem cells from cell-sorted umbilical cord blood. Global epigenetic analysis was performed on 43 newborn infants, 18 of whom were delivered with planned caesarean section. Furthermore, DNA from twelve newborns (six planned cesarean sections) was analyzed for gene-specific epigenetic change throughout the genome.

The results show specific epigenetic differences between the groups at nearly 350 sites in the genome. The genes with different methylation patterns were involved, among other things, in processes that control the metabolism and the immune system.

The study provides support for the theory that the act of giving birth itself leaves imprints in the genome of the newborn baby’s stem cells. The discovery may be important to understand why people born with caesarean section are statistically at increased risk for immunological diseases. However, it is still unclear whether the so-called epigenetic change is temporary or persists for a long time. The biological mechanisms that predispose a fetus or newborn to diseases later in life are complex and depend on both inheritance as well as environment during the fetal stage and throughout adolescence (which I wrote about earlier).

But what could this “good” stress* be positive for?

One possible explanation is that during a vaginal delivery, the fetus is subjected to a progressively increasing and very strong stress onset, which here is positive for the child and prepares it for life outside the uterus. This stress is believed to activate the child’s defense system for adaptation to life after birth, which is absent in planned Caesarean sections where the work of labor never starts. However, it is important to remember that many immunological diseases, including those mentioned above, are a result of both inheritance and the environment, and that our epigenome is not static but is affected by our internal and external environment throughout our lives.

Finally, I sometimes can’t help but think that no matter how much advanced technology and knowledge we get, we often cannot circumvent biology. Maybe something to comfort yourself with the next time you think back on your (or your partner’s) labor. Or when you’re breathing through the pain of your upcoming labor. And to those who have had emergency C-sections: those hours of pain pre-cesarean were actually useful. So don’t despair!

(This post does not try to blame or act as a pointing stick. My view is that every woman decides over her own body and knows what it can and does best. For many, planned caesarean sections are a medical necessity. As I see it, knowledge is power to be able to make sensible decisions and change the world in a positive direction.)

* However, it should be clarified that the type of stress we are talking about here is not the same as chronic, long-term, stress. Which has on the contrary been shown to have negative health effects (which I do not go into here).

Louise Sjöholm has an education in molecular biology and a doctorate in depression genetics from Karolinska Institutet. She has been working as an epigeneticist for seven years and is researching the role of the gastrointestinal tract in autoimmune diseases, i.e., diseases in which the body’s immune system attacks its own tissue. She is also interested in understanding the epigenetics of bacteria and its connection to health and disease. The views in the chronicle are the writer’s own.

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