Study links C-section birth to obesity

Findings of an ongoing study involving 22,068 young adults in the U.S. over a 16-year period

Updated - December 05, 2016 09:24 am IST

Published - December 04, 2016 08:57 pm IST - Thiruvananthapuram:

The rising rates of C-sections the world over and concerns over the potential long-term implications of the procedure for women have always made news.

In many public- and private-sector hospitals in the State, C-section rates go well over 50 per cent.

If the discussions till now were all about women’s bodies and their informed choices, there has been a growing body of evidence linking C-section deliveries to the future outcome of those babies.

Large-scale studies done in the U.S. and Denmark now confirm that C-section births may not exactly be benign and that such babies are at higher risk of being obese or suffering from chronic illnesses later in life.

A National Institutes of Health-funded study carried out by researchers from various institutions, including the Harvard School of Public Health, analysed data on 22,068 young adults from the ongoing Growing Up Today Study (GUTS), in the U.S. over a 16-year period.

The results, reported in the journal JAMA Paediatrics in September, said there was a clear association between C-section delivery and increased risk of obesity in offspring that persisted through early adult life.

Babies born by C-section had a 64 per cent increased risk of being obese in later life, in comparison to their siblings born by vaginal delivery.

Children born by vaginal delivery to mothers who had a previous C-section had a 31 per cent lower risk of obesity when compared to their sibling born by repeat C-section.

In yet another giant study, which examined the correlation between C-sections and immunological disorders, in two million Danish children born over a period of 35 years between 1973 and 2012, scientists reported that children born by C-section were more frequently sick with asthma, juvenile rheumatoid arthritis, immune systems defects, and other tissue disorders during their lives.

More specifically, the risk of developing asthma was 20 per cent higher if the child was born by a C-section, the study found. The results were reported in the January 2015 issue of JAMA Paediatrics.

Both these giant studies did not say that C-section deliveries were the direct cause of obesity or chronic disorders, but the correlation is well-established. The C-section procedure itself definitely increased the risk of obesity in later life.

And the explanation is fascinating.

Researchers believe that the most “compelling mechanism” supporting the association between C-sections and obesity/chronic disorders are the differences in gut microbiota.

At birth, one’s body is colonised by bacteria. The first bacteria that babies born normally gets exposed to are those in their mother’s gut and birth canal. In the case of babies born by C-section, the first exposure is to the bacteria on the mother’s skin and the hospital bacteria. This initial difference in the mode of delivery has a huge effect on the gut microbiota of babies and their immune systems, it seems.

Other hypotheses include: blood immune markers are different at birth in babies born by Caesarean than born vaginally and the induction of stress hormone (cortisol) seems to be lower in C-section babies, which may affect immune system maturation.

There is not enough evidence at present to say that C-section surgery itself leads to immunological disorders but it is possible that it is one of the environmental factors that triggers the immune system.

“There is increasing evidence from across the world, which confirms that child birth is not a mechanical event and that it is a neuro-endocrine, epigenetic and microbiome formation process, which can have life-long effects on the offspring,” says Simone Diniz, Head of the Department of Maternal and Child Health, School of Public Health, University of Sao Paulo, Brazil, who was in the city recently.

A renowned scholar who has a body of seminal work in the area of gender, maternal health and evidence-based care, Dr. Diniz says that a well-indicated C-section is indeed a very important, life-saving medical resource. But women are often misled into believing that it is the best option for them and their babies.

The new evidence linking the chronology of the global rise in non-communicable diseases and that of C-section rates should prompt doctors and pregnant women to think twice about more informed choices and C-sections that are not medically necessary, she says.

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