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Category: pregnancy and childbirth

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Two studies showing detrimental effects on children from pyrethroids in 2 weeks! The June 3 post was about research linking household pyrethroid exposure to ADHD in children and young teens. The second study found that low level childhood exposures to pyrethroid insecticides was linked to lower scores on an IQ test (Wechsler Intelligence Scale for Children - verbal comprehension and working memory) in 6 year old children. The researchers viewed this as evidence that pyrethroid insecticides may "negatively affect neurocognitive development".

Bottom line: even though pyrethroid pesticides are considered safer than many other pesticides, they still can have undesirable effects on humans, especially developing children. To be safe, use least toxic pest control that uses non-toxic, safe "alternative" or "natural" methods rather than just "spraying a chemical". Another possibility is looking for "organic pest control" or"least-toxic Integrated Pest Management" (IPM) that looks to deal with pest problems with non-toxic methods (which may include sealing holes, heat, caulking, trapping, using sticky traps, and even vacuuming up insects). From Science Daily:

Impact of insecticides on the cognitive development of 6-year-old children

Researchers have provided new evidence of neurotoxicity in humans from pyrethroid insecticides, which are found in a wide variety of products and uses. An increase in the urinary levels of two pyrethroid metabolites (3-PBA and cis-DBCA) in children is associated with a significant decrease in their cognitive performances , particularly verbal comprehension and working memory. This study was carried out on nearly 300 mother and child pairs from the PELAGIE cohort (Brittany).

Pyrethroids constitute a family of insecticides widely used in a variety of sectors: agriculture (various crops), veterinary (antiparasitics) and domestic (lice shampoo, mosquito products). Their mode of action involves blocking neurotransmission in insects, leading to paralysis. Because of their efficacy and relative safety for humans and mammals, they have replaced older compounds (organochlorides, organophosphates, carbamate) considered more toxic.

Exposure of children to pyrethroids is common. It is different to adult exposure, due to the closer proximity of children to ground-level dust (which stores pollutants), more frequent hand-to-mouth contact, lice shampoos, etc. In children, pyrethroids are mainly absorbed via the digestive system, but are also absorbed through the skin. They are rapidly metabolised in the liver, and mainly eliminated in the urine as metabolites within 48 hours.

Pregnancy is also an important period of life for the future health of the child. For this reason, the researchers studied the PELAGIE mother-child cohort established between 2002 and 2006, which monitors 3,500 mother-child pairs. This cohort simultaneously considers exposure to pyrethroid insecticides during fetal life and childhood. A total of 287 women, randomly selected from the PELAGIE cohort and contacted successfully on their child's sixth birthday, agreed to participate in this study.

Two psychologists visited them at home. One assessed the child's neurocognitive performances using the WISC scale (verbal comprehension index, VCI, and working memory index, WMI). The other psychologist characterised the family environment and stimuli that might have had a role on the child's intellectual development, collected a urine sample from the child, and collected dust samples. Exposure to pyrethroid insecticides was estimated by measuring levels of five metabolites (3-PBA, 4-F-3-PBA, cis-DCCA, trans-DCCA and cis-DBCA) in urine from the mother (collected between the 6th and 19th weeks of pregnancy) and from the child (collected on his/her 6th birthday).

Results show that an increase in children's urinary levels of two metabolites (3 PBA and cis-DBCA) was associated with a significant decrease in cognitive performances, whereas no association was observed for the other three metabolites (4-F-3-PBA, cis-DCCA and trans-DCCA). With respect to metabolite concentrations during pregnancy, there was no demonstrable association with neurocognitive scores.

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Another good reason to breastfeed. Exposure to pollutants like nitrogen dioxide and airborne particles can cause negative effects on motor and mental development in infants, but a new study says those effects are countered in babies who are breast-fed for at least 4 months by their mothers. Researchers in Spain began monitoring rural, pregnant women in 2006 and analyzed samples from 638 women and their infants at 15 months. They reported that babies who are breast-fed did not suffer from the potentially harmful developmental impact of PM2.5 (pollution particle matter) and NO2 (nitrogen dioxide). From Science Daily:

Breastfeeding protects against environmental pollution

Living in a city with a high level of vehicle traffic or close to a steel works means living with two intense sources of environmental pollution. However, a study conducted by the UPV/EHU researcher Aitana Lertxundi indicates that the harmful effect of PM2.5 pollution particle matter and nitrogen dioxide (NO2) disappears in breastfed babies during the first four months of life. According to the results of the research, breastfeeding plays a protective role in the presence of these two atmospheric pollutants.

Lertxundi's study focusses on the repercussions on motor and mental development during the first years of life caused by exposure to the PM2.5 and NO2 atmospheric pollutants .... "In the fetal phase the central nervous system is being formed and lacks sufficient detoxification mechanisms to eliminate the toxins that build up," pointed out Aitana Lertxundi.

The PM2.5 particles measure less than 2.5 micra, in other words, they are four times thinner that a single hair and are suspended in the air. As they are so small they can easily penetrate the body and as they weigh so little they can spread without any difficulty through the air and can move far away from the initial emission source. The composition of these neurotoxic particles depends on the emission sources in the area. The INMA Gipuzkoa area under study has a high presence of neurotoxic particle matter made up of lead, arsenic and manganese from industrial activity and traffic. In comparison with urban averages where the main source of pollution is traffic, the concentration is lower.

One result of the study is that the existence of an inverse relationship has been detected between exposure to pollution particle matter and the motor development of babies. In this respect, the researcher highlights the fact that "these indices display an alteration with respect to the average and, even if they are not worrying, they are significant in that they reveal the relationship existing between air quality and motor development." The analysis of the data also shows that neither the PM2.5 particle matter nor the NO2 exert a harmful effect on babies breastfed on mother's milk for at least four months.

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In a newly published study looking at how infant gut microbes change over time, once again babies had differences in gut bacteria depending on whether they were delivered vaginally or by Cesarean section.

But what's interesting is that stopping breastfeeding changed their gut bacteria  more (to more adult-like species) than just introducing solid foods. Certain types of bacteria thrive on the nutrients breast milk provides and once these nutrients are no longer available, then other bacteria emerge that are more commonly seen in adults. In other words, stopping breastfeeding seems to drive "maturation" of the gut bacteria.

From The Scientist: Maturation of the Infant Microbiome

Like babies themselves, the intestinal microbiomes of infants start out in an immature state and over time grow into communities similar to those of adults. In a new survey of 98 Swedish babies whose microbiota were sampled several times during their first year of life, researchers found that the microbiomes of breastfed infants persisted in a “younger” state longer than those of non-breastfed babies, even after the introduction of solid foods.

The conclusion that “stopping breastfeeding—rather than introducing solids—drives maturation is a new idea, because we all thought so far that solids introduction was a key factor in changing the microbiota,” said Maria Gloria Dominguez-Bello, a microbiologist at New York University School of Medicine who did not participate in the study.

Researchers from University of Gothenburg in Sweden and their colleagues found more adult-like taxa in the microbiomes of babies who stopped breastfeeding earlier, while the microbiota of babies breastfed for longer were dominated by bacteria present in breastmilk. The results, published today (May 13) in Cell Host & Microbe, are part of an effort to catalog the microbial changes that occur as children age and to note how those changes correlate with health and disease. Fredrik Bäckhed of Gothenburg and his colleagues collected stool samples from 98 moms and their newborns, and again sampled the babies’ stool at four and 12 months.

Confirming previous work, his team’s analysis found that the 15 babies born via cesarean section were colonized by different bacteria—many from oral and skin communities—than babies born vaginally, who shared numerous microbes with those present in their mothers’ stool.

For instance, in the vaginally delivered newborns’ microbiomes, genes that break down sugars in breastmilk were common. As these babies celebrated their first birthdays, the genes in their microbiomes favored the ability to breakdown starches, pectins, and more complex sugars.

“What’s nice about this paper is that they show this maturation [of the microbiome] in normal, healthy kids in a Western population follows this transition based on diet,” said Steven Frese, a postdoc at the University of California, Davis, who penned a commentary accompanying the study with his advisor, David Mills. “Being exposed to new foods promotes the growth of new bacteria that can consume them,” Frese told The Scientist.

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Currently, during birth there are many potential disruptions to the healthy development of the infant's microbial ecosystem. Some practices to be concerned about: the use of antibiotics during pregnancy and during delivery, c-sections, newborns routinely given antibiotics, and then bottle feeding instead of breastfeeding. Sometimes one or more of these practices are medically necessary, but currently they are being done much too frequently and casually. In these ways we are conducting an experiment on every baby's microbial ecosystem with unknown long-term consequences. The following excerpts from Dr.Martin Blaser's popular 2014 book Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues, even though written a year ago, are a nice summary of these issues. From Wired:

The Way You’re Born Can Mess With the Microbes You Need to Survive

THROUGHOUT THE ANIMAL kingdom, mothers transfer microbes to their young while giving birth....And for millennia, mammalian babies have acquired founding populations of microbes by passing through their mothers’ vagina. This microbial handoff is also a critical aspect of infant health in humans. Today it is in peril.

Microbes play a hidden role in the course of every pregnancy. During the first trimester, certain species of bacteria become overrepresented while others become less common. By the third trimester, just before the baby is born, even greater shifts occur. These changes, involving scores of species, are not random. The compositions change in the same direction across the dozens of women who have been studied.... Women of reproductive age carry bacteria, primarily lactobacilli, which make the vaginal canal more acidic. This environment provides a hardy defense against dangerous bacteria that are sensitive to acid. Lactobacilli also have evolved a potent arsenal of molecules that inhibit or kill other bacteria.

Whether the birth is fast or slow, the formerly germ-free baby soon comes into contact with the lactobacilli. The baby’s skin is a sponge, taking up the vaginal microbes rubbing against it. The first fluids the baby sucks in contain mom’s microbes, including some fecal matter.

Once born, the baby instinctively reaches his mouth, now full of lactobacilli, toward his mother’s nipple and begins to suck. The birth process introduces lactobacilli to the first milk that goes into the baby. This interaction could not be more perfect. Lactobacilli and other lactic acid–producing bacteria break down lactose, the major sugar in milk, to make energy. The baby’s first food is a form of milk called colostrum, which contains protective antibodies. The choreography of actions involving vagina, baby, mouth, nipple, and milk ensures that the founding bacteria in the baby’s intestinal tract include species that can digest milk for the baby.

Breast milk, when it comes in a few days later, contains carbohydrates, called oligosaccharides, that babies cannot digest. But specific bacteria such as Bifidobacterium infantis, another foundational species in healthy babies, can eat the oligosaccharides. The breast milk is constituted to give favored bacteria a head start against competing bacteria.

Cesarian delivery is a largely unrecognized threat to the microbial handoff from mother to child. Instead of traveling down the birth canal picking up lactobacilli, the baby is surgically extracted from the womb through an incision in the abdominal wall....For all of these reasons, U.S. C-section rates increased from fewer than one in five births in 1996 to one in three births in 2011—a 50 percent increase.

The founding populations of microbes found on C-section infants are not those selected by hundreds of thousands of years of human evolution. A few years ago in Puerto Ayacucho, Venezuela, my wife, Gloria, conducted the first study of its kind to test whether the microbes found on newborn babies delivered vaginally or by C-section varied in any way....The mouths, skin, and first bowel movements of babies born vaginally were populated by their mother’s vaginal microbes: Lactobacillus, Prevotella, or Sneathia species. Those born by C-section harbored bacterial communities found on skin, dominated by Staphylococcus, Corynebacterium, and Propionibacterium.

In other words, their founding microbes bore no relationship to their mother’s vagina or any vagina. At all the sites—mouth, skin, gut—their microbes resembled the pattern on human skin and organisms floating in the air in the surgery room. They were not colonized by their mother’s lactobacilli. The fancy names of these bacteria don’t matter as much as the notion that the founding populations of microbes found on C-section infants are not those selected by hundreds of thousands of years of human evolution or even longer.

Another threat to a baby’s newly acquired resident microbes involves antibiotics given to the mother. Most doctors consider it safe to prescribe penicillins for all sorts of mild infections in pregnancy—coughs, sore throats, urinary tract infections. Sometimes when doctors think that the mother has a viral infection they also give antibiotics just in case it is actually a bacterial infection.

Then comes the birth itself. Women in labor routinely get antibiotics to ward off infection after a C-section....Antibiotics are broad in their effects, not targeted....The problem, of course, is that we know antibiotics are broad in their effects, not targeted. While the antibiotic kills Group B strep, it also kills other often-friendly bacteria, thus selecting for resistant ones. This practice is altering the composition of the mother’s microbes in all compartments of her body just before the intergenerational transfer is slated to begin.

The baby also is affected in similar unintended ways. Any antibiotic that gets into the bloodstream of the fetus or into the mother’s milk will inevitably influence the composition of the baby’s resident microbes, but we are only beginning to understand what this means.

Finally, the babies are directly exposed. Most parents are not aware that all American-born babies today are given an antibiotic immediately after birth. The reason is that many years ago, before antibiotics, women who unknowingly had gonorrhea would pass the infection to their babies, giving the newborns terrible eye infections that could cause blindness...The dose is low but is likely affecting the composition of the infant’s resident microbes just when the founding populations are developing. We should be able to develop a better way to screen, so we can target those babies at the highest risk, perhaps a few hundred among the millions of births a year.

Although babies are born into a world replete with diverse bacteria, the ones that colonize them are not accidental. These first microbes colonizing the newborn begin a dynamic process. We are born with innate immunity, a collection of proteins, cells, detergents, and junctions that guard our surfaces based on recognition of structures that are widely shared among classes of microbes. In contrast, we must develop adaptive immunity that will clearly distinguish self from non-self. Our early-life microbes are the first teachers in this process, instructing the developing immune system about what is dangerous and what is not.

A newborn infant, seconds after delivery. Amniotic fluid glistens on the child's skin.  Credit: Wikipedia, Ernest F

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There has been a lot of discussion in the last few years of our gut bacteria (hundreds of species), the microbiome (the community of microbes living within and on a person (gut, nasal cavities, mouth, sinuses, etc.), probiotics, the finding of a link between bacteria and some chronic diseases, and how the modern lifestyle and antibiotics are wiping out our beneficial gut microbes. I am frequently asked how one can improve or nurture the beneficial bacteria in our bodies.

While no one knows what exactly is the "best" or "healthiest" microbial composition of the gut, it does look like a diversity of bacteria is best (may make you healthier and more able to resist diseases). Research also suggests that the diversity and balance of bacteria living in the body can be changed and improved, and changes can occur very quickly. And that the microbial communities fluctuate for various reasons (illness, diet,etc.). Diet seems to be key to the health of your gut microbial community. Prebiotics feed the beneficial bacteria in the gut, probiotics are live beneficial bacteria, and synbiotics are a combination of prebiotics and probiotics. But don't despair - you can improve your gut microbial community starting now. The following are some practical tips, based on what scientific research currently knows.

SOME STEPS TO FEED AND NURTURE YOUR GUT MICROBES:

Eat a wide variety of foods, especially whole foods that are unprocessed or as minimally processed as possible. Eat everything in moderation.

Eat a lot of plant based foods: fruits, vegetables, whole grains, seeds, nuts, and legumes. Think of Michael Pollan's advice: "Eat food. Not too much. Mostly plants."

Eat more washed and raw fruits and vegetables (lots of bacteria and fiber to feed and nurture the bacteria). Some every day would be good.

Eat more soluble and insoluble types of fiber, and increase how many servings you eat every day. A variety of  fiber foods every day, and several servings at each meal, is best. Think fruits, vegetables, whole grains, legumes, nuts, seeds. (See How Much Dietary Fiber Should We Eat? - also has a chart with high fiber foods, and Recent Studies Show Benefits of Dietary Fiber)

Eat as many organic foods as possible. There is much we don't yet know, and pesticides are like antibiotics - they kill off microbes, both good and bad. Somehow I think that lowering the levels in your body of pesticides (as measured in blood and urine) can only be beneficial. Also, organic foods don't contain added antibiotics and hormones. (Eat Organic Foods to Lower Pesticide Exposures).  But even if you can't or won't eat organic foods, it is still better to eat non-organic fruits, vegetables, and whole grains than to not eat them.

Eat some fermented foods such as kimchi and sauerkraut (they contain live bacteria), kefir, and yogurts with live bacteria. Eat other bacteria containing foods such as cheeses, and again a variety is best (different cheeses have different bacteria).

Try to avoid or eat less of mass-produced highly processed foods, fast-foods, preservatives, colors and dyes, additives, partially hydrogenated oils, and high-fructose corn syrup. Read all ingredient lists on labels, and even try to avoid as much as possible "natural flavors" (these are chemicals concocted in a lab and unnecessary). Even emulsifiers (which are very hard to avoid) are linked to inflammation and effects on gut bacteria.

Avoid the use of triclosan or other "sanitizers" in soaps and personal care products (e.g., deodorants). Triclosan promotes antibiotic resistance and also kills off beneficial bacteria. Wash with ordinary soap and water.

Avoid unnecessary antibiotics (antibiotics kill off bacteria, including beneficial bacteria).

Vaginal births are best - microbes from the birth canal populate the baby as it is being born. If one has a cesarean section, then one can immediately take a swab of microbes from the mother's vagina (e.g., using sterile gauze cloth) and swab it over the newborn baby. (See post discussing this research by Maria Gloria Dominguez Bello )

Breastfeeding is best - breastfeeding provides lots of beneficial microbes and oligosaccharides that appear to enrich good bacteria in the baby’s gut.

Live on a farm, or try to have a pet or two. Having pets, especially in the first year of life,  ups exposure to bacteria to help develop and strengthen the immune system, and prevent allergies. Pets such as dogs and cat expose humans to lots of bacteria.

Get regular exercise or physical activity. Professional athletes have more diverse gut bacterial community (considered beneficial) than sedentary people.

Can consider taking probiotics - whether in foods or supplements. They are generally considered beneficial, but not well studied, so much is unknown. The supplements are unregulated, and the ones available in stores may not be those that are most commonly found in healthy individuals. Research the specific bacteria before taking any supplements. Researchers themselves tend to stay away from probiotic supplements and focus on eating a variety of all the foods mentioned above (fruits, vegetables, whole grains, seeds, nuts, legumes, fermented foods) to feed and nurture beneficial bacteria.

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Scientists warn about endocrine disruption from 4 common chemicals in an analysis just released. This is absolutely depressing because the 4 chemicals (benzene, toluene, ethylbenzene, xylene) are so pervasive in indoor air. Especially that at levels considered "safe" by the EPA there may be disruption of our hormones (endocrine systems).

Of course the 4 chemicals are already known to have health effects on the human body other than what is discussed in this study. For example, toluene has a number of central nervous system effects. The EPA says toluene , which is found in highest concentrations in indoor air from the use of common household products (paints, paint thinners, adhesives, synthetic fragrances, and nail polish). Outside - the biggest source of toluene is from automobile emissions.

Some ways to lower exposure to these 4 chemicals: Read product labels. When using a product that says to use with proper ventilation - open the windows and let the room ventilate!  Don't smoke. (For example: the EPA says tobacco smoke contains benzene and accounts for nearly half the national exposure to benzene) The study researchers themselves said the EPA should be paying more attention to these air contaminants. I read this at Scientific American, but the following excerpts are from EHN.

From EHN: Scientists warn of hormone impacts from benzene, xylene, other common solvents.

Four chemicals present both inside and outside homes might disrupt our endocrine systems at levels considered safe by the U.S. Environmental Protection Agency, according to an analysis released today. ...continue reading "More Problems With Four Common Chemicals"

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The research finding that eating fruits and vegetables with high pesticide residues has a negative effect on sperm is disturbing. It wasn't the amount of fruits and vegetables eaten, it was eating fruits and vegetables with high levels of pesticide residues. Yes, the study does have some limitations (for example, a one time analysis, looked at men at a fertility clinic and not the general population), but...even with these limitations, the results are disturbing.

Earlier studies of children showed that switching to an organic diet has almost immediate results of reducing pesticide residues in the body (OP Pesticides in Children’s Bodies: The Effects of a Conventional versus Organic Diet). So the advice here is try to increase the amounts of organic fruits and vegetables in the diet, especially those with high pesticide residue levels.

Fruit or vegetables that were low in pesticide residues included peas, beans, grapefruit and onions. Those that had highest pesticide residues included peppers, spinach, strawberries, celery,blueberries, potatoes, peaches, plums, apples and pears.

From Time: A Diet High in Pesticides Is Linked to a Lower Sperm Count

The troubling link between pesticide exposure and fertility isn’t new; scientists have already established that people who work with pesticides tend to have lower fertility than people who don’t. But for the majority of us who don’t work with chemicals, diet is the biggest source of exposure, says Jorge Chavarro, MD, assistant professor of nutrition and epidemiology at Harvard School of Public Health and senior author of a new study published in the journal Human Reproduction.

Chavarro and his colleagues wanted to see if pesticide residues left on fruits and vegetables might have a similar effect on sperm—and their findings suggest that they did. Men who ate fruits and vegetables with a lot of pesticides had lower sperm counts and more oddly shaped sperm than those who had lower levels of dietary pesticide exposure.

Over an 18-month period, the researchers used data from the Environment and Reproductive Health (EARTH) study, including semen samples from 155 men who were being treated at a Boston fertility clinic and a food frequency questionnaire they completed. The researchers determined pesticide exposure by comparing the questionnaire answers with government data about produce pesticide levels in the USDA’s Pesticide Data Program.

The study didn’t tease out individual foods, but the researchers classified produce according to whether it had high or low-to-moderate levels of pesticides. Men who ate the most high-pesticide fruits and vegetables had a 49% lower total sperm count and 32% fewer sperm that were shaped normally, compared to men who ate the least amount of the high-pesticide produce.

Researchers gave each piece of produce a score based on its level of detectable pesticides, its level of pesticides that exceeded the tolerance level established by the U.S. Environmental Protection Agency, and whether the produce had three or more types of detectable pesticides. (The bigger the score, the more it hit all three measures.) Ranked from highest pesticide contamination to lowest, here were the top fruits and vegetables: Green, yellow and red peppers (6), Spinach (6), Strawberries (6), Celery (6), Blueberries (5), Potatoes (5), Peaches and plums (5), Apples or pears (5), Winter squash (4), Kale, mustard greens and chard greens (4), Grapes and raisins (4).

The team didn’t tease out associations with individual pesticides. But they believe that a mixture of pesticides—not just one particular pesticide—is responsible for the link. The strongest variable in their analysis were the proportion of fruits and vegetables consumed that use three or more pesticides. “The more pesticides are applied on any particular crop, that seems to be having a bigger impact,” Chavarro says...But for people who are concerned about their dietary exposure to pesticides, there are ways to lower it, he says, like eating organic and choosing produce not listed on the Environmental Working Group’s dirty dozen list.

From Science  Daily: Pesticides in fruit and vegetables linked to semen quality

Assistant Professor of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health in Boston (USA), Jorge Chavarro, said: "These findings should not discourage the consumption of fruit and vegetables in general. In fact, we found that total intake of fruit and vegetables was completely unrelated to semen quality. This suggests that implementing strategies specifically targeted at avoiding pesticide residues, such as consuming organically-grown produce or avoiding produce known to have large amounts of residues, may be the way to go."

There were no differences seen between men in the four groups who consumed fruit and vegetables with low-to-moderate pesticide residues. In fact, there was a significant trend towards having a higher percentage of normally shaped sperm among men who consumed the most fruit and vegetables with low pesticide residues -- a relative increase of 37% from 5.7% to 7.8%...Note:Pesticide use varies from country to country, but in the USA those used on fruit and vegetables include Atrazine, Malathion, Chlorpyrifos and Carbendazim. 

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Healthy women were followed during their pregnancies and postpartum, and it was found that vaginal microbial communities change over the course of pregnancy, and then really change postpartum. They also found differences in the predominant Lactobacillus bacteria species between the women. In this study it was found that Lactobacillus bacteria were most dominant during pregnancy, especially L. gaserii, L. crispatus, L. iners, and L. jensenii, and there were ethnic differences in the species. And they found that the vaginal microbiome changes postpartum, with bacteria becoming more diverse and the numbers of Lactobacillus dropping. The message here is that what are "normal and healthy" microbial communities can vary between women (in this study which Lactobacillus species were "healthy and normal" varied among women). Remember: dysbiosis means that the normal microbial community is "out of whack". And sequenced the microbiomes means state of the art genetic analysis of the microbial communities From American Microbiome Institute:

The vaginal microbiome changes during and after pregnancy

The vaginal microbiome is critically important to a healthy pregnancy, and studies have shown that vaginal dysbiosis during pregnancy can lead to infection and preterm birth.  In order to help understand what the microbiome looks like throughout and just after pregnancy, researchers from England performed longitudinal studies on 42 pregnant women.  They published their results last week in Nature Scientific Reports.

The scientists sequenced the microbiomes of the 42 women throughout their pregnancies, and then for the 6 weeks afterwards for some of the women.  They discovered, in agreement with other literature on the subject, that the vaginal microbiome becomes dominated by Lactobacilli species during pregnancy.  The Lactobacilli are thought to prevent pathogens from colonizing the vagina because they produce lactic acid which decreases the overall pH of the vagina, and they secrete antibacterial toxins.  These Lactobacilli are also important as they are normally the first to colonize the new infants' guts after they pass through the birth canal. 

The researchers also learned that the microbiome shifts away from Lactobacilli and towards a more diverse microbiome in the period immediately following birth.  The new bacteria that colonize are often associated with vaginosis, and these can lead to inflammation and infection of the birth canal in some women.  The scientists suspect this shift occurs because there is a sudden drop in estrogen production upon removal of the placenta.  The increase in circulating estrogen is thought to be important for Lactobacilli colonization, so it makes sense that the rapid decrease in estrogen decreases Lactobacilli abundance.

Finally, this study showed that there were geographic and ethnic variations to the pregnant microbiome.  While each microbiome was associated with a healthy pregnancy, there were important differences, especially on the species level.  For example, Asian and Caucasian women’s pregnant microbiomes were dominated by Lactobacillus gasseri, while this species was absent in black women’s pregnant microbiomes.

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Research is accumulating that the microbial exposure from a vaginal birth, breastfeeding, and pets in the first year of life are all good for a baby's developing immune system and the gut microbiome.

From Science Daily: Breastfeeding, other factors help shape immune system early in life

Researchers say that breastfeeding and other factors influence a baby's immune system development and susceptibility to allergies and asthma by what's in their gut. The striking findings from a series of studies further advance the so-called hygiene hypothesis theory that early childhood exposure to microorganisms affects the immune system's development and onset of allergies, says Christine Cole Johnson, Ph.D., MPH, chair of Henry Ford's Department of Public Health Sciences and principal research investigator.

The gut microbiome is the collection of microorganisms in the gastrointestional, or GI, tract, and the human body has billions of these microbes... The gut microbiome is known to play an important role in immune system development, and is thought to contribute to a host of diseases like obesity, autoimmune diseases, circulating disorders and pediatric allergies and infection.

"For years now, we've always thought that a sterile environment was not good for babies. Our research shows why. Exposure to these microorganisms, or bacteria, in the first few months after birth actually help stimulate the immune system," Dr. Johnson says."The immune system is designed to be exposed to bacteria on a grand scale. If you minimize those exposures, the immune system won't develop optimally."

In six separate studies, researchers sought to evaluate whether breastfeeding and maternal and birth factors had any effect on a baby's gut microbiome and allergic and asthma outcomes. Using data collected from the WHEALS birth cohort, researchers analyzed stool samples from infants taken at one month and six months after birth. They also looked at whether the gut microbiome impacted the development of regulatory T-cells, or Treg, which are known to regulate the immune system. Highlights:

• Breastfed babies at one month and six months had distinct microbiome compositions compared to non-breastfed babies. These distinct compositions may influence immune system development. • Breastfed babies at one month were at decreased risk of developing allergies to pets. • Asthmatic children who had nighttime coughing or flare-ups had a distinct microbiome composition during the first year of life. • For the first time, gut microbiome composition was shown to be associated with increasing Treg cells.

Researchers found that a baby's gut microbiome patterns vary by: • A mother's race/ethnicity. • A baby's gestational age at birth. • Prenatal and postnatal exposure to tobacco smoke. • Caesarean section versus vaginal delivery.• Presence of pets in the home.

Henry Ford's landmark 2002 study found exposure to dogs or cats in the first year of a baby's life reduced their risk for allergies.

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More than a year after California revised its flame retardant standards so that new furniture (the polyurethane foam in upholstered sofas, sofa beds, and chairs) does not have to use flame retardants, it is still hard to find out whether the furniture is flame retardant free. This is what I have experienced in the last few months - the store doesn't know and the manufacturer won't respond to emails.

The new furniture label should say TB 117-2013 , and then you still need to ask the retailer if there are flame retardants in the upholstered furniture. The new label means that the manufacturer does NOT have to use flame retardant chemicals anymore, but it does NOT mean they are chemical free. And flame retardants are still found in many baby products (car seats, bumpers, crib mattresses, strollers, nursing pillows, etc), some personal care products, and electronics. It's a buyer beware situation.

More and more research is finding health problems with flame retardants because they are "not chemically bound" to the products in which they are used - thus they escape over time, and get into us via the skin (dermal), inhalation (from dust), and ingestion (from certain foods and dust on our fingers). And because flame retardants are persistant, they bioaccumulate (they build up over time). They can be measured in our urine and blood.

Evidence suggests that flame retardants may be endocrine disruptors, carcinogenic, alter hormone levels, decrease semen quality in men, thyoid disruptors, and act as developmental neurotoxicants (when developing fetus is exposed during pregnancy)  so that children have lowered IQ and more hyperactivity behaviors.

How does one know if the foam in your furniture has flame retardants in it? Duke University will test it for free if you send them a small piece of the furniture's foam. http://sites.nicholas.duke.edu/superfund/whats-in-my-foam/ I originally read about this service a few months ago in The Atlantic,

From The Atlantic: How to Test a Couch for Toxins

It began with a smell. Kerri Duntley had just bought a pair of large, cream-colored couches....As the scent continued to fill her living room, Duntley asked herself a troubling question: What was causing the couches to smell like industrial chemicals? The answers weren’t easy to find. Duntley searched in web forums and even tried contacting the couches’ manufacturer. “I called and called and called,” she said. “They just would not give me the information.” She grew frustrated and began looking for new couches. It was then that she discovered an unusual service run by a Duke University lab.

The lab’s offer was simple. First, the lab instructed, wield a pair of scissors. Grab something made with polyurethane foam—say, a mattress or the innards of a couch cushion. Cut a small chunk from the foam. Wrap the surgical work in tinfoil, ziplock seal it and mail the crime-scene-looking evidence off to Durham, North Carolina. Wait up to 45 days, the lab said, and it’ll arrive: a report detailing toxic flame retardants embedded in the foam.

Duntley complied. When the results came back, she learned that her couch sample had tested positive for two flame retardants, including one that has proven harmful in animal studies, a finding that she called heartbreaking. Her experience points to a vast gap in safety information about consumer goods. With the U.S. government’s limited power to regulate chemicals, many consumers, like Duntley, are left to piece together their own crude health-risk assessments. That fabric softener? It may smell like the Elysian Fields, but what if its unlisted ingredients cause cancer? 

Government officials , academic researchers, the chemical industry and environmentalists agree: The U.S. system of chemical regulation is broken. But while the fight over reform continues in Washington, consumers remain blind to many of the chemicals that enter their homes.

Duke’s service is looking in its small way to change that. The lab—which offers anyone a free chemical analysis of polyurethane foam—has informed hundreds of Americans about their furniture’s toxicity. At the same time, the foam samples have given Duke’s team a large bank of crowdsourced research. By offering a free service to an anxious public, Duke’s scientists are gaining a clearer view of chemical manufacturing. And they’re learning just how much we don’t know about the chemicals that enter our homes.

Stapleton was part of a scientific cohort that found ingesting dust—say, getting our dusty hands on a burger—is by far our largest source of exposure to flame retardants; flame retardants aren’t chemically bound to their products, and so they attach themselves to airborne dust.

But what began in California soon became a de facto national standard, since furniture companies didn’t want to manufacture separate lines. Stapleton was interested to see how chemically saturated our furniture really is. So she and her colleagues asked families for samples of their baby products’ foam. After reviewing 101 samples from across thirteen states, Stapleton’s 2011 study reached a startling conclusion: Flame retardants accounted for about 5 percent of the products’ weight, and the chemicals were found in 80 percent of the samples.

Some of the chemicals were carcinogens. Others were from a chemical class known as polybrominated diphenyl ethers, or PBDEs, which have been linked to lower IQ scores, attention deficit hyperactivity disorder, and thyroid disorders. The most common flame retardant among the samples was tris (1,3-dichloroisopropyl)phosphate, or TDCPP, which researchers say is likely to harm the neurological development of infants. TDCPP, in fact, was used throughout the 1970s in children’s pajamas, until critical health research led manufacturers in 1977 to stop using it. Yet the chemical had reemerged in products like strollers and baby mattresses.

The lab offered to test some of these strangers’ furniture for free. But the requests kept coming. That’s when Stapleton and her colleagues decided to expand the scope of the testing and conceived of a free service for the public. They’d test anyone’s polyurethane foam for a suite of seven common flame retardants as something of a public service, since it would be funded by a federal grant (itself funded by taxpayer dollars). The service would also aid Stapleton’s research, offering a valuable stream of crowdsourced data about the chemicals used in furniture.

By crowdsourcing her research, Stapleton has also uncovered a flame retardant that academic literature has yet to identify. The flame retardant is a chlorinated organophosphate, like TDCPP, and its health effects are unknown, she said. Stapleton said that this recent discovery-by-accident followed the same pattern as her research on Firemaster 550, a popular flame retardant that replaced two widespread PBDEs after they were withdrawn from the market... But emerging research has raised concerns about Firemaster 550, too. One study from Boston University and Duke researchers found that the chemical mixture may cause obesity in humans. Stapleton found the same effect in rats.