C-Section Births Cause Genetic Changes That May Increase Odds For Developing Diseases In Later Life
ScienceDaily (June 29, 2009) — Swedish researchers have discovered that babies born by Caesarean section experience changes to the DNA pool in their white blood cells, which could be connected to altered stress levels during this method of delivery, according to the July issue of Acta Paediatrica.
It is thought that these genetic changes, which differ from normal vaginal deliveries, could explain why people delivered by C-section are more susceptible to immunological diseases such as diabetes and asthma in later life, when those genetic changes combine with environmental triggers.
Blood was sampled from the umbilical cords of 37 newborn infants just after delivery and then three to five days after the birth. It was analysed to see the degree of DNA-methylation in the white blood cells - a vital part of the immune system.
This showed that the 16 babies born by C-section exhibited higher DNA-methylation rates immediately after delivery than the 21 born by vaginal delivery. Three to five days after birth, DNA-methylation levels had dropped in infants delivered by C-section so that there were no longer significant differences between the two groups.
“Delivery by C-section has been associated with increased allergy, diabetes and leukaemia risks” says Professor Mikael Norman, who specialises in paediatrics at the Karolinska Institutet in Stockholm, Sweden. “Although the underlying cause is unknown, our theory is that altered birth conditions could cause a genetic imprint in the immune cells that could play a role later in life.
“That is why we were keen to look at DNA-methylation, which is an important biological mechanism in which the DNA is chemically modified to activate or shut down genes in response to changes in the external environment. As the diseases that tend to be more common in people delivered by C-section are connected with the immune system, we decided to focus our research on early DNA changes to the white blood cells.”