Children who are born by Caesarian section may have an increased risk of immune deficiency-related illnesses later in life compared to those who are born by natural birth, according to new research from the Karolinska Institute in Stockholm.

"Researchers at Karolinska Institutet have discovered that babies born by planned Caesarean section experience changes to the DNA pool in their white blood cells," the Karolinska Institute says.

"Our results provide the first pieces of evidence that early so called epigenetic programming of the immune system during birth may have a role to play," says Professor Mikael Norman of the Institute's Department of Clinical Science, Intervention and Technology.

Increased risk
The Institute says that the findings, which are presented in the July issue of the scientific journal Acta Paediatrica, may be part of the explanation as to why babies born by Caesarean section have an increased risk of developing certain immunological diseases such as diabetes, asthma or leukaemia in later life.

In the Karolinska study, blood was sampled from the umbilical cords of 37 newborns just after delivery and then again three to five days after the birth and analysed to see the degree of chemical alteration of DNA in white blood cells.

"This showed that the 16 babies born by Caesarean section exhibited higher DNA-methylation rates immediately after delivery than the 21 born by vaginal delivery," the Institute says.

Back to normal
Three to five days after birth, the levels had dropped in infants delivered by Caesarean section so that there were no longer significant differences between the two groups, the study shows, and researchers say it is unclear why DNA changes are higher after Caesarean section deliveries.

"Although we do not yet know how specific gene expression is affected after Caesarean section deliveries, or to what extent these genetic differences related to mode of delivery are long-lasting, we believe that our findings open up a new area of important clinical research" says the main author of the report, Karolinska Institute Research Fellow Titus Schlinzig.