AN EXTEMSIVE study, conducted in the USA and published in Jama Pediatrics, found that children born by cesarean section were 15% more likely to become obese than those delivered vaginally. The risk was particularly significant between siblings, with those born by cesarean 64% more likely to be obese than a brother or sister delivered vaginally.

The genetic risks of becoming obese are generally similar for siblings in the same family. However, a new American study, based on data from 22,000 young adults over 16 years, has revealed one factor that could affect metabolism long-term: being born by C-section.

The researchers identified a link between birth by C-section and obesity risk. In fact, a sibling born by cesarean was 64% more likely to become obese than a brother or sister with the same parents delivered vaginally.

The scientists studied participants' body mass index (BMI) over time, how they were born (C-section or vaginally) and other factors that could play a role in obesity, like their mothers' BMI before pregnancy, smoking status, age at delivery and where they lived. They also looked at whether the participants' mothers had previous C-section deliveries.

They found that individuals born by C-section were 15% more likely to become obese than those delivered vaginally. The study also suggests that this increased risk may persist through adulthood.

Children of women who gave birth vaginally after previous C-section deliveries were 31% less likely to become obese compared with those born via C-section following a previous C-section birth.

A C-section is a surgical procedure used to deliver a baby. The procedure is carried out in an operating theater under anesthetic, usually an epidural. In certain cases, C-section deliveries can be carried out under general anesthetic.

C-section deliveries can be recommended in cases of placenta previa, abnormal presentation and for multiple births, for example. Ultrasound scans and prenatal examinations can help identify cases in which C-section delivery may be preferable.