Scientists have been discovering some interesting things about obesity. In fact, whether a child is born naturally or via Caesarian section may play a very important role. New research suggests that some simple steps taken during a C-section operation could make a lifetime of difference. Unfortunately, it probably won't.
Americans are well aware that the country is suffering the effects of an increasingly obese population. It's well known that healthcare costs are skyrocketing. While there are many reasons healthcare costs are out of control, one that is gaining increasing recognition is obesity.
Medical experts have suspected for a while that those born via C-section – typically about 10 – 15% of births – tend to be more prone to asthma, autoimmune diseases, and obesity. The question, of course, is why. Once the "why" is understood, can something then be done?
A theory that's emerged in the past few years is that one's microbiome – the constellation of bacteria each of us has both over and within our bodies – plays an important role. The bacteria in our individual microbiomes have an influence on how food is digested, and there's evidence that many people are cursed by biomes that increase the propensity for weight gain. To some extent, we inherit our biomes from our mother.
As part of the birth process, it appears that at least part of the mother's microbiome passes to the baby. But the outcome appears to be different depending upon whether there is a natural birth or a C-section. Doctors and other medical researchers have determined that in natural birth, the baby picks up the mother's microbiome. In contrast, children born via C-section seem only to pick up the microbiome of the mother's skin, so the C-section baby doesn't pick up as much protection. The question is, why?
Two hypotheses have been proposed. One is that the C-section process itself somehow robs the child of the additional microbiome protection. One theory is that as the baby passes through the birth canal, it gains protection, almost an "extra protective coating". The other hypothesis is that the antibiotics used as part of the C-section surgery itself may kill off parts of the mother's microbiome that would otherwise be transferred to the baby. An obvious way to test this would be to do some C-sections without antibiotics – a form of controlled experiment – but the attendant risks make that type of experiment unacceptable.
Dr. Maria Gloria Dominguez-Bello has been performing some interesting experiments to try to figure out the answer. In one set of experiments, she and her associates put a piece of sterile gauze in the vagina of the mother about one hour before the C-section surgery was to be performed. The gauze was left in place until just before the surgery began. Once removed, the gauze was placed in a sterile container. After the baby's birth, doctors then swabbed the gauze over the newborn baby, beginning with the eyes and lips, then other parts of the body. In effect, the goal was to simulate the "coating" of the baby's body with the mother's microbiome as the baby passed through the birth canal.
Dominguez-Bello and her team studied 18 births. Of these, 7 were born vaginally and 11 by C-section. Of those born via C-section, 4 were exposed to the mother's vaginal fluid using the gauze and 7 were not. The results? The team tested the C-section infants and found that their microbiomes looked like those of the vaginally delivered infants, and contrasted with the C-section infants who were not swabbed. This suggests that the trip through the birth canal makes a real difference. The results were published in March, 2016.
Do the antibiotics of a typical C-section make a difference? To test that hypothesis, Dominguez-Bello and her team conducted another study, published in Science Advances in October, 2017. In this experiment, the scientists compared 35 natural mouse births with 34 births via C-section. No antibiotics were used in the 34 C-section births. It was determined that the C-section mice did not inherit the microbiomes of their mothers in the same way that the natural birth mice did. Since no antibiotics were used, one can then rule out the possibility that antibiotics somehow killed off the "biome transfer" as an unintended side effect of the C-section.
These are promising experiments. The scientists, however, expressed a note of caution because the sample sizes were very small. The preliminary conclusion is that the natural birth process does seem to confer a benefit on the baby, which seems to translate into a lower risk of obesity later in life. Based upon the "gauze experiment", it might not be surprising to see "baby swabbing" as an additional procedure conducted as part of ordinary C-section births in the future.
That might provide some benefits, but it certainly won't be a "magic bullet". In fact, by the time the baby is about to be born, the "obesity dice" may already have been cast. The Harvard School of Public Health has identified three other key factors, each of which seems to come into play during pregnancy and before the birth event itself:
- Maternal smoking
- Gestational weight gain
- Mother's blood sugar during pregnancy.
A meta-analysis of 14 pre-natal smoking studies found a 50% higher risk of obesity in offspring whose mother's smoked. Likewise, the Harvard researchers also found that if the mother had excessive weight gain during pregnancy, the child was four times as likely to be overweight at age 3. Blood sugar levels of the mother during pregnancy also seemed to predict excess weight in the child.
Then there seem to be another set of factors that come into play after the baby is born, irrespective of whether the child was born naturally or via C-section. Three post-birth factors appear to be most important:
- #1: How rapidly the child gains weight after birth
- #2: How long the child is breast fed
- #3: How much sleep the child gets.
With respect to #1, researchers found that if a child gains weight too rapidly, there is a greater risk of later life obesity. Breast feeding, as well as how long a child is breast fed, are also factors. Breast feeding seems to reduce the risk of later obesity, particularly if it occurs for at least 12 months. In terms of sleeping, the more sleep a child gets in the first year of life, the lower the risk of later obesity.
Combining all of these factors together, a study called Project Viva found that the children whose mothers didn't smoke during pregnancy, did not gain too much weight, were breastfed for at least one year, and who got an average of at least 12 hours of sleep per night, had only a 6% chance of becoming obese. Given that 10-15% of all births are by C-section, there's a good chance that 1% of those 6% might have become obese only because they were born via C-section.
Preventing obesity early in life certainly makes sense, but combining all of this together suggests that it won't be easy because there are so many possible factors involved, including pre-natal, the birth process itself, and post-natal.
At the same time, with the possible exception of C-sections themselves, every one of the risk factors cited seems to involve fairly commonsense things that shouldn't be controversial, and should not be difficult to implement. After all, it's common sense that:
- Women who are pregnant should not smoke, should not gain too much weight during pregnancy, and should be careful about their blood sugar levels;
- Mothers with infants should to take steps to avoid too much weigh gain in the child; should breast feed the child, preferably for a year; and should make sure the child gets at least 12 hours of sleep/might.
Except that it doesn't seem to be happening, at least for a fairly significant percentage of mothers. The Project Viva data, cited earlier, suggested that only about 6% of young children should be obese. Unfortunately, data suggest that over the past decade, about 17% of children are obese. In the case of Latinos, it's around 21%.
The rates of obesity seem to be increasing. Data show that for children aged 6 – 11 years, the obesity rate has increased from 4% in the 1971-74 time frame to 18% in 2009-10. For adolescents, it's gone from 6.1% to 18.4%.
So attention can, and should, be focused on getting children off to a healthy start in life, through proper pre-natal care, good birth care, and early life care. But if close to one fifth of adolescents are obese, we've got a problem that extends way beyond how mothers are caring for children through the first year of life.
What makes this especially scary is when you consider the financial cost of obesity. Most everyone realizes that waistlines are getting bigger, but how does that translate in terms of total healthcare spending? Recently, it was estimated that fully 21% of medical spending in the USA is somehow related to obesity - $ 190.2 billion in the latest reported year. To put that in perspective, this "obesity related healthcare spending" represents more than the entire economies of the majority of countries in the world!
A good example of the problem is what happens when ordinary people show up at a hospital emergency room with chest pains. If someone is overweight, the cost pretty much automatically goes up. How much? Here's a comparison of cost versus the cost of a person of normal weight:
- Overweight (but not obese) 22% more
- Obese 28% more
- Severely obese 41% more.
Most healthcare spending is on the elderly. Nothing surprising about that. But think back to those statistics I cited earlier about the change in obesity levels over time. Back in 1971-74, 4% of children were obese. Four to five times as many are obese today. If we're spending at our current rate on healthcare, and a fifth of spending is on obesity-related conditions, what's going to happen when the percentage of elderly people who were themselves obese as children quintuples?
I don't have an answer. The Dominguez-Bello research cited earlier is certainly exciting, and may provide part of the answer. I just think we need to realize there's no simple answer to the problem of obesity, but the problem is so big and scary, we need to find the answers to it.