Saturday, May 14, 2011

Caesarean risk: New research finds C-section babies are more likely to become obese in later life

Probably just the usual class effect: Poorer people are more likely to be obese and more likely to have poor health generally -- thus necessitating more Caesars. But the explanation highlighted below is reasonable too. Either way it's not the Caesar itself that causes obesity

Babies born by caesarean section are at greater risk of becoming obese in later life than those delivered naturally, researchers have found. The obesity epidemic could be partly driven by rising rates of surgical deliveries, although the reasons for this are unclear, their study suggests.

The report, in the American Journal of Clinical Nutrition, says lack of exposure to beneficial bacteria in the birth canal could explain the link.

However, the children of fatter mothers are also more likely to have weight problems. Given that obesity in pregnancy is a risk factor that leads to more caesarean section births, it may be that this relationship between the weight of mother and child explains the findings.

In the study, Brazilian researchers looked at obesity rates in 2,000 people aged 23 to 25. They found 15 per cent of those delivered by caesarean were obese compared with 10 per cent of those born naturally.

The study analysed a number of factors that might explain the connection, including heavier birthweight, income and education levels, because women with more qualifications had a higher caesarean rate. But even after accounting for these factors, being born by caesarean was linked to a 58 per cent increase in the risk of obesity in adulthood.

Dr Helena Goldani, who carried out the study with colleagues at the Universidade Federal de Rio Grande do Sul in Porto Alegre, said the findings did not prove a causal link between surgical deliveries and weight problems.

But she explained that, because infants born surgically are not exposed to beneficial bacteria in the birth canal, they might take longer to accumulate good bugs which affect the metabolism. Obese adults tend to have fewer of these friendly bacteria in their digestive tract than normal-weight people.

The theory is that having fewer good intestinal bugs leads to the body burning fewer calories and storing more of them as fat. But other experts said there was a ‘huge gap in the data’. They said it was difficult to interpret the study because it did not include any information on the mother’s weight while pregnant.

Dr Ian Campbell, medical director of Weight Concern, said the study ‘raises more questions than it answers’. He said: ‘This is a very interesting finding, which is difficult to interpret without knowing the weight of the mothers while pregnant.

‘However, women who have a caesarean are less likely to breastfeed, which helps prevent obesity in children by establishing a healthier weight in childhood.’ ‘There are many different ways of influencing obesity in adulthood and this is another area for research,’ he added.

Around 23 per cent of all births in the UK are by caesarean section. The World Health Organisation recommends the figure should be around 15 per cent.

Brazil, where the study was done, has around 44 per cent of babies delivered by caesarean section. Many of those procedures are thought to be medically unnecessary.


Depressed and anxious? You could have had stomach problems as a baby

This is drawing a very long bow indeed. All that they found was that giving rats stomach irritation stressed them. They then found that giving them an antidepressant relieved the stress. What is new or surprising in that I fail to see

Stomach complaints such as irritable bowel syndrome could result in depression, a surprising study suggests. Scientists at Stanford University found short-term digestive irritation early in life could have massive implications for mental health later on.

'A lot of research has focused on understanding how the mind can influence the body,' said lead author Dr Pankaj Pasricha. 'But this study suggests that it can be the other way around. Gastric irritation during the first few days of life may reset the brain into a permanently depressed state.'

As not all stomach upsets lead to lifelong psychological problems the impact may depend on when it occurs during a person's development. It could also be related to their genetic makeup.

About one in five people experience persistent or recurring pain in the upper abdomen, suffering from conditions such as IBS. Researchers have long noted that these people are also more likely than their peers to be anxious or depressed.

Up until now it was assumed that stress hormones associated with a patient's altered mood were responsible for their digestive problems. However, Dr Pasricha believes the opposite could be true noting that many patients date their gastrointestinal problems back to early childhood, before their psychological symptoms started. Therefore he suggests these digestive disturbances could cause mood disorders.

His theory has been bolstered by recent research that has linked depression and anxiety in humans to changes in the composition of gut bacteria. 'The gut and the brain are hardwired together by the vagus nerve, which runs from the brain to the body's internal organs,' Dr Pasricha said. 'The communication between the gut and the adult brain is elaborate and bi-directional, and changes in the gut are signaled directly to the brain.'

To test their hypothesis they subjected 10-day-old laboratory rats to mild stomach irritation daily for six days. 'We hypothesized that this treatment might also be affecting the development of central nervous system, and driving the animals to anxiety and depression,' said Dr Pasricha.

Eight weeks later researchers found that the treated rats were far more likely than their peers to display depressed and anxious behaviors, including drinking less sugar water, less-active swimming and keeping to dark areas in a maze. They also had increased levels of the stress hormones corticosterone and corticotrophin.

Blocking the animals' ability to perceive sensation from their gut with a drug did not affect their behavior, indicating that the rats were not responding to ongoing pain. However, inhibiting the activity of a hormone known to be associated with depression in humans and animals, caused the treated rats to behave more normally in the tests.

'It seems that when the rats are exposed to gastric irritation at the appropriate point in time,' said Dr Pasricha. 'There is signaling across the gut to the brain that permanently alters its function.'

The researchers are now planning to investigate exactly how that signaling is initiated and acts in the brain, and whether it might be possible to develop new ways to treat depression and anxiety in humans. 'We'd like to know whether the vagus nerve is involved, and confirm what changes may occur in the brain in response to this signal,' said Dr Pasricha.

'The vast majority of humans don't experience any long-lasting consequences from transient infections. But there may be subset of patients who are genetically predisposed to this effect by mechanisms we don't yet understand yet. '

In particular, electrical stimulation of the vagus nerve has recently been approved by the Food and Drug Administration for treatment-resistant depression; this research may help researchers better understand and optimize this new approach .

The study has been published in PLoS One.


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