Pediatric Research 2014: The Year's Most Interesting Studies

Alan Greene, MD; Laurie Scudder, DNP, PNP


September 08, 2014

In This Article

A Look to the Future

Medscape: Are there any other recent studies that you would like to discuss?

Dr. Greene: An interesting recently published study[18] casts doubt on our long-standing belief that a developing baby was in a sterile, protected environment in the mother. The thinking goes that when the amniotic sack breaks and the baby comes through the vaginal canal, that the infant is colonized by mom's vaginal flora, and ends up with a healthy gut microbiome as a result. We've come to understand that this is really important, and it is one of the reasons why kids who are born by cesarean section, for instance, have a higher risk for allergic rhinitis and an increased asthma risk. More or less, that's been the story.

A recent study examined changes in the maternal vaginal microbiome during pregnancy and the effects of this change on the infant's health.[18] The researchers found that indeed, the vaginal flora during pregnancy is different from the vaginal flora when the mother is not pregnant. What was surprising was that the mother's vaginal microbiome was also very different -- in fact, not related at all to the new gut microbiome that colonized the baby. That just made no sense. How could that be?

Looking further, the investigators determined that the baby is being colonized from the placental microbiome. The baby was not developing in a sterile environment, as we have all believed for years, but rather in an environment with small numbers of beneficial bacteria that end up becoming the gut microbiome of the baby. This idea of a placental microbiome is brand new to me.

Then they looked to see what this placental microbiome most resembled, and it was not the vaginal microbiome. It was not the mom's gut, skin, or nasal microbiome. Instead, it is her oral microbiome that is the closest match. Although there are still unanswered questions, it looks like it may be that beneficial bacteria from the mother's mouth feed the placenta hematogenously. That would help explain such things as the link between periodontal disease and preterm birth.

Incidentally, investigators also found that the babies who were born early tended to have different species in their early microbiome than the ones who were born on time. And the babies born to women who had had an infection during pregnancy -- for example, a urinary tract infection treated with antibiotics -- had different gut microbiome as well. So we're still just learning, but the role of beneficial bacteria is greater than we ever thought and is an important thing to which we need to pay attention.

Another interesting report that I would like to briefly note is a paper titled Teaching Nutrition and Physical Activity in Medical School: Training Doctors for Prevention-Oriented Care, jointly released in June 2014 by the Bipartisan Policy Center, the American College of Sports Medicine, and the Alliance for a Healthier Generation. The authors reported that 75% of doctors do not feel competent talking about nutrition. Only 1 in 8 clinical encounters mentioned nutrition of any kind, and fewer than 30% of medical schools provide even the minimum recommended hours of nutrition training during medical school.

If you look at many of the rapidly increasing health problems in kids -- hypertension, type 2 diabetes, abnormal cholesterol levels, abnormal triglyceride levels, waist size over 40 inches -- they require nutritional guidance from clinicians. It is something we need to learn about. We have a nutritional crisis in kids in our country.

The childhood obesity epidemic is just a visible symptom of a problem with how kids eat. Data from the National Health and Nutrition Examination Survey confirm that kids are getting a huge percentage of their calories from white-flour sweets, such as cookies and cakes; pizza; and soda.[19] The only vegetables on the list of the top 25 sources of calories in children between the ages of 2 and 18 years are French fries and potato chips. Unless you count pizza as a vegetable. If cheese pizza is a vegetable -- which in the school lunch program it is -- then there are 3 vegetables on that list. We have to do better.

The final study I'd like to note is one that does not have immediate practical implications but is of interest nevertheless. Researchers examining the effect of analgesics in rodents found that they weren't able to replicate their studies between laboratories.[20] Drugs seemed to work well in some settings and other times did not, and so they wanted to find out why.

It turned out that it depended on who the researchers were. Drugs tested by male researchers had one effect; tests conducted by women found a different effect. And it wasn't just that. If a T-shirt that had been worn by a man was left in the lab with the rodents, there was a different pain response than if a T-shirt worn by a woman was left in the room.

It appears these rodents had what looks like a fight-or-flight response with exposure to a male, and it changed the appearance of the drug response. This is very interesting and calls into question a lot of research where we have seen subtle differences in responses. We have a lot still to learn about the ways in which we are all connected that are invisible to us most of the time.


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