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Category: pregnancy and childbirth

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After my January 9, 2015 post I was asked more about the microbial differences in babies who had been born by cesarean vs vaginal deliveries. What could be done about this? Should this be of concern when C-section rates in some places are approaching 50% of all births?

Well, some researchers are concerned, including Dr. Dominguez-Bello, who is doing ground-breaking research in this area. She is doing a long-term study in which babies born by cesarean section are immediately swabbed with a gauze cloth laced with the mother's vaginal fluids and resident microbes. Several (but not all) articles that I looked at said that the gauze is a "saline-soaked gauze".

Summary of the method:1) Incubate gauze in mother's vagina for 1 hour 2) Extract gauze before C-section  3) Expose newborn to the vaginal gauze (Mouth first, then face, then rest of body). If for some medical reason they don’t (and there is a C-section), then this is a restoring intervention.

Note that Dr. Dominguez-Bello always first checks to make sure the mother is HIV-negative and strep-B negative, and showing no signs of a STD. The basic premise is that babies should have crossed the mother's birth canal to be "seeded" with the mother's microbes, but if for some medical reason they don’t (and there is a C-section), then this is a (somewhat) restoring intervention.

From Feb. 2014 New York Academy of Sciences: Hats Off to Bacteria!

Why are bacteria in the body? What do we, and the bacteria, gain from this arrangement? And who's in charge? "There is a dialogue," Dominguez-Bello said, "sometimes a fight, sometimes a good dialogue. We have evolved with them. The first form of life on Earth was bacteria. Whatever came after had to deal with bacteria, cope with bacteria, associate with bacteria ...  ...continue reading "Can Missing Birth Canal Bacteria Be Restored to Cesarean Birth Babies?"

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Nice write-up of how what happens from the type of birth (vaginal vs cesarean) affects the baby's microbiome (community of microbes). Remember, it is very complicated and much is still unknown. (UPDATE: see January 16, 2015 post discussing research by Dr. Dominguez-Bello who is conducting a study in which babies born via C-section are immediately swabbed with their mother's vaginal secretions; these babies will then be followed for years). From Gastroenterology and Endoscopy News:

Delivery Mode Alters Newborn’s First Bacterial Exposure

 A baby’s first exposure to bacteria varies by the method of delivery, researchers have found. These differences could have health implications later in life, according to an emerging body of evidence that suggests gut bacteria may be important to the development of a healthy immune system (Arrieta MC et al.Front Immunol 2014;5:427). For example, evidence shows that alterations in gut bacteria early in life may increase the incidence of allergies later on (Bendiks M, Kopp MV. Curr Allergy Asthma Rep 2013;13:487-494).

In the new study, presented at the 2014 annual meeting of the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, a group at the University of Colorado School of Medicine, in Aurora, compared oropharyngeal aspirates taken from 12 infants born by cesarean delivery and 11 born vaginally, and their bacterial content by sequencing the bacterial genes in the samples (abstract 7). Samples taken from the mothers’ vaginal and rectal areas, and samples of the infants’ stool, were also analyzed for bacterial genes.

Bacteria in aspirates from newborns delivered vaginally were more similar to the bacteria found in samples from their mothers than the aspirates from infants born by cesarean delivery, the investigators found. Infants born vaginally had higher numbers of firmicutes (62.6% vs. 30.1%; P=0.0013), particularly lactobacilli typically found in the vagina.

Aspirates from infants born by cesarean delivery, in contrast, had higher levels of Actinobacteria (20.1% vs. 3.8%; P=0.045), which are found on the skin. Stool samples from vaginally delivered newborns also had greater numbers of Bacteroidetes than stool samples from infants born by cesarean delivery. This difference persisted through six weeks of life, the researchers said.

David Brumbaugh, MD, assistant professor of pediatrics at the University of Colorado School of Medicine, in Aurora, said the finding of fewer Bacteroidetes in cesarean newborns is potentially alarming. Studies of mice raised in sterile conditions have shown that exposure to a specific type of Bacteroidetes, Bacteroides fragilis, suppresses the animals’ inflammatory response (Mazmanian SK et al. Nature 2008;453:620-625), he said. 

“The fact that this bacteria never gets established early in life [in babies born by cesarean delivery] is concerning,” he said. Some studies have suggested that infants born by cesarean delivery may be at greater risk for developing conditions such as asthma, type 1 diabetes and celiac disease (Cho CE, Norman M. Am J Obstet Gynecol 2013;208:249-254). But not all studies have supported such risks; other studies suggest that genetic factors or the reason for the cesarean delivery itself may contribute to disease later in the child’s life (Almqvist C et al.Clin Exp Allergy 2012;42:1369-1376).

Jean-Eric Ghia, PhD, assistant professor of immunology and internal medicine at the University of Manitoba, in Winnipeg, Canada, said the findings add to a body of evidence suggesting that gut bacterial colonization is affected by mode of delivery, and these altered gut bacteria might contribute to immune system–related disease later in life (Neu J, Rushing J.Clin Perinatol 2011;38:321-331). “The first colonization of the gut happens when the baby comes out,” he said. But he noted that long-term studies are needed to assess the effect of these gut differences on health in the long term. He noted that a multitude of exposures before and after birth can also influence gut biota (Munyaka PM et al. Front Pediatr. doi:10.3389/fped.2014.00109 [published online October 9, 2014]). “It’s really, really complicated,” he said.

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Something to think about if you are considering fathering a child.From Medical Xpress:

Study links ultraviolet filters to pregnancy delays

Certain sunscreen chemicals used to protect against ultraviolent rays may impair men's ability to father children in a timely manner, according to a study by the National Institutes of Health and the New York state Department of Health's Wadsworth Center. But the researchers caution that the results are preliminary and that additional studies are needed to confirm their findings.

Benzophenone (BP)-type ultraviolet (UV) filters comprise a class of about 29 chemicals commonly used, among other purposes, in sunscreens and other personal care products to protect skin and hair from sun damage. Some of these chemicals, upon being absorbed by the skin, can interfere with the body's hormones and endocrine system processes. Researchers found that men with high exposure to UV filters BP-2 or 4OH-BP had a 30 percent reduction in fecundity, the biological ability to reproduce. Lower fecundity may result in a longer time to pregnancy.

"In our study, male fecundity seems to be more susceptible to these chemicals than female fecundity. The women participants actually had greater exposure to the UV filters overall, but their exposure wasn't associated with any significant pregnancy delays," said Germaine Louis, Ph.D., director of the Division of Intramural Population Health Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development. 

The researchers studied 501 couples that were trying to conceive a child. The couples were part of the Longitudinal Investigation of Fertility and the Environment (LIFE) study, established to examine relationships among fertility, lifestyle factors, and exposure to environmental chemicals. Researchers recruited the study participants from 16 counties in Michigan and Texas in 2005 through 2009. The women participants ranged from 18 to 44 years of age, and the men were over 18; none had a medical diagnosis of infertility.

The researchers followed the couples until pregnancy or up to one year of trying, to record the time it took for the women to become pregnant...Their findings suggest that some, but not all, UV filters may be associated with diminished fertility in men, independent of their partners' exposure. The researchers observed effects among men with the highest exposure (the 75th percentile and above) to UV filters BP-2 or 4OH-BP.

"But men who are concerned about fertility may be interested in other ways to reduce their exposure to benzophenone UV filters—whether by cutting back on other products that contain the UV filters or by washing after returning indoors."

Earlier research findings from the LIFE Study have linked reduced fertility to high cholesterol levels in women and couples and to high concentrations of phthalates and Bisphenol A (BPA) in men.

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Once again air pollution is linked to health problems, this time exposure during pregnancy is linked to congenital malformations (what are commonly called birth defects). From Science Daily:

Smoke signals: New evidence links air pollution to congenital defects

The health effects of air pollution are a major concern for urban populations all over the world. A new study provides new evidence linking high exposure to air pollution to an increased risk of congenital malformations. Children, the elderly, and people with impaired respiratory systems (such as asthmatics) tend to be especially sensitive to the impact of exposure to ozone, nitrogen dioxide, sulphur dioxide, and particulate matter.

A recent study by Tel Aviv University researchers provides new evidence linking high exposure to air pollution to an increased risk of congenital malformations. The nationwide study is the first to assess the association between different modes of conception-assisted reproductive technology (ART) versus spontaneous conception (SC) -- and the risks of exposure to air pollution to each.

"Our results suggest that exposure to higher levels of air pollution during pregnancy is associated with various adverse pregnancy outcomes," said Prof. Lerner-Geva. "While our study mainly followed SC infants, we also had the opportunity to assess a small sample of pregnancies that were conceived through ART, and observed a higher impact of air pollution -- particularly with regard to ozone exposure. This is clearly a uniquely susceptible population that should be further explored."

For the study, funded by the Environmental Health Fund (EHF), the research team analyzed data on 216,730 born in Israel between 1997 and 2004. Air pollution data, including, levels of sulfur dioxide (SO2), particulate matter (PM10), nitrogen oxides (NOx), and ozone (O3) were obtained from air monitoring stations for the study period. Using a geographic information system, exposure to air pollution during both the first trimester and the entire pregnancy was assessed for each woman according to her place of residence.

The researchers found that exposure to PM10 and NOX pollutants throughout full-term pregnancies were associated with an increased risk of congenital malformations, with specific defects evident in the circulatory system (from PM10 and NOX exposure) and genital organs (from NOX exposure). They also discovered that exposure to SO2 and O3 in ART pregnancies were associated, although not significantly, with a higher risk of congenital defects.

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Two studies finding various forms of air pollution having effects on the developing fetus - the first one (fine particulate air pollution) to autism, and the second (outgassing of new flooring) to later breathing problems.

From Medical Xpress: Fine particulate air pollution linked with increased autism risk

Women exposed to high levels of fine particulate matter specifically during pregnancy—particularly during the third trimester—may face up to twice the risk of having a child with autism than mothers living in areas with low particulate matter, according to a new study from Harvard School of Public Health (HSPH). The greater the exposure, the greater the risk, researchers found. It was the first U.S.-wide study exploring the link between airborne particulate matter and autism.

"Our data add additional important support to the hypothesis that maternal exposure to air pollution contributes to the risk of autism spectrum disorders," said Marc Weisskopf, associate professor of environmental and occupational epidemiology and senior author of the study.... Prior studies have suggested that, in addition to genetics, exposure to airborne environmental contaminants, particularly during pregnancy and early life, may affect risk of autism. This study focused specifically on the pregnancy period.

The study population included offspring of participants living in all 50 states in Nurses' Health Study II, a cohort of more than 116,000 female U.S. nurses begun in 1989. The researchers collected data on where participants lived during their pregnancies as well as data from the U.S. Environmental Protection Agency and other sources on levels of fine particulate matter air pollution (PM2.5)—particles 2.5 microns in diameter or smaller—in locations across the U.S. The researchers identified 245 children who were diagnosed with autism spectrum disorder (ASD) and a control group of 1,522 children without ASD during the time period studied.

Exposure to PM2.5 was significantly associated with autism during pregnancy, but not before or after, the study found. And during the pregnancy, the third trimester specifically was significantly associated with an increased risk. Little association was found between air pollution from larger-sized particles (PM10-2.5) and autism.

From Science Daily: New floor covering can lead to breathing problems in babies

New flooring in the living environment of pregnant women significantly increases the risk of infants to suffer from respiratory diseases in their first year of life. This is the result of a study that demonstrates that exposure to volatile organic compounds in the months before and after birth induces breathing problems in early childhood. The scientists therefore recommend that redecoration should be avoided during pregnancy or in the first year of children’s life.

The observed health risks are caused by increased concentrations of volatile organic compounds (in short: VOCs), such as styrene or ethylbenzene, which escape from new flooring and are then absorbed through the respiratory air. "We therefore do not recommend that laminate, carpet or floor coverings be laid in the homes of pregnant women. Although the concentrations of these volatile chemicals are lower if no adhesive is used when installing the flooring, even then the concentrations are still high enough to significantly increase the risk of infants suffering from respiratory complaints in their first few months," explains Dr. Ulrich Franck from the UFZ. 

Earlier studies from Leipzig had already shown that chemicals from home renovations lead to changes in the immune system of new-born children.... According to our results, exposure to these volatile chemical compounds seems to be more critical in pregnancy than in the first year of a child's life," concludes Dr. Irina Lehmann from the UFZ, who is in charge of the LINA study on lifestyle and environmental factors and their influence on the risk of allergies in newborn babies. An analysis of the data showed that renovations after the birth of a child had a much lower impact on respiratory problems than during pregnancy.

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Avoid unnecessary ultrasounds because there is an effect on the fetus, even if it's just a temporary effect. Medical associations warn against getting ultrasounds during pregnancy without a real reason. From The Atlantic:

FDA Warning: Stay Away From 'Keepsake' Ultrasounds

The medically unnecessary scans peddled by businesses—often set up in malls and administered by people with no healthcare training—may pose a health risk to both fetus and mother.

Despite repeated warnings by the Food and Drug Administration over the years, commercial ultrasound businesses—often set up in shopping malls and run by untrained technicians—continue to offer their services to expectant parents. And consumers, despite the FDA’s pleas, continue to pay for them, shelling out hundreds of dollars for photos or videos of their developing fetus (and fueling a thriving Etsy niche, where ultrasound images can be turned into ultrasound cufflinks, pillows, cake toppers, and truly unsettling night lights.)

Earlier today, the agency issued the latest of a long line of alerts against non-medical ultrasounds and heartbeat monitors, reminding consumers that “both are prescription devices designed to be used by trained healthcare professionals … only when there is a medical need, based on a prescription,” and that “the FDA strongly discourages their use for creating fetal keepsake images and videos.”

Ultrasounds, which use sound waves to produce an image, are considered a safe and valuable diagnostic tool during pregnancy, when they can provide information on the fetus' age, sex, and overall health. But “ultrasound can heat tissues slightly, and in some cases, it can also produce very small bubbles in some tissues,” FDA biomedical engineer Shahram Vaezy said in the alert. Because the long-term effects of the heating are unknown, these gratuitous ultrasounds, which provide no medical information, may pose a small but unecessary risk to both mother and fetus—compounded by the fact that their duration, and the qualifications of the people administering them, aren't subject to regulation.... (Researchers have recently focused on ultrasound as a possible method of male contraception, noting that it dramatically lowers sperm count when applied to the testicles.)

Several medical groups have also come out against commercial ultrasounds over the years, including the American Medical Association, the American College of Obstetricians and Gynecologists, the American College of Radiology, the American Institute of Ultrasound in Medicine, and the American Pregnancy Association.

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This research finding of lower IQ in children with higher exposure to 2 common phthalates during pregnancy is very troubling. Especially since avoiding all phthalates in the USA is currently impossible. But one can lower levels in the body by reading all ingredients and trying to avoid certain products (e.g. dryer sheets, vinyl shower curtains, personal care products with phthalates, scented products). And don't microwave food in plastic containers. From Science Daily:

Prenatal exposure to common household chemicals linked with substantial drop in child IQ

Children exposed during pregnancy to elevated levels of two common chemicals found in the home -- di-n-butyl phthalate and di-isobutyl phthalate -- had an IQ score, on average, more than six points lower than children exposed at lower levels, according to researchers.

DnBP and DiBP are found in a wide variety of consumer products, from dryer sheets to vinyl fabrics to personal care products like lipstick, hairspray, and nail polish, even some soaps. Since 2009, several phthalates have been banned from children's toys and other childcare articles in the United States. 

Researchers followed 328 New York City women and their children from low-income communities. They assessed the women's exposure to four phthalates--DnBP, DiBP, di-2-ethylhexyl phthalate, and diethyl phthalate--in the third trimester of pregnancy by measuring levels of the chemicals' metabolites in urine. Children were given IQ tests at age 7.

Children of mothers exposed during pregnancy to the highest 25 percent of concentrations of DnBP and DiBP had IQs 6.6 and 7.6 points lower, respectively, than children of mothers exposed to the lowest 25 percent of concentrations after controlling for factors like maternal IQ, maternal education, and quality of the home environment that are known to influence child IQ scores. The association was also seen for specific aspects of IQ, such as perceptual reasoning, working memory, and processing speed. The researchers found no associations between the other two phthalates and child IQ. The range of phthalate metabolite exposures measured in the mothers was not unusual: it was within what the Centers for Disease Control and Prevention observed in a national sample.

"A six- or seven-point decline in IQ may have substantial consequences for academic achievement and occupational potential.""While there has been some regulation to ban phthalates from toys of young children," adds Dr. Factor-Litvak, "there is no legislation governing exposure during pregnancy, which is likely the most sensitive period for brain development. Indeed, phthalates are not required to be on product labeling."

While avoiding all phthalates in the United States is for now impossible, the researchers recommend that pregnant women take steps to limit exposure by not microwaving food in plastics, avoiding scented products as much as possible, including air fresheners, and dryer sheets, and not using recyclable plastics labeled as 3, 6, or 7.

The findings build on earlier, similar observations by the researchers of associations between prenatal exposure to DnBP and DiBP and children's cognitive and motor development and behavior at age 3. This September, they reported a link between prenatal exposure to phthalates and risk for childhood asthma. It's not known how phthalates affect child health. However, numerous studies show that they disrupt the actions of hormones, including testosterone and thyroid hormone. Inflammation and oxidative stress may also play a role.

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Another research result from the American Gut Project, an amazing crowdsourced project. While differences were found in the fecal microbiome (microbial community) of adults born by cesarean section vs vaginal delivery, it is unknown whether this has any possible effects on diseases or risks of diseases during adulthood. This study is online as of 8 November 2014, but still In Press. From EBioMedicine:

Diversity and Composition of the Adult Fecal Microbiome Associated with History of Cesarean Birth or Appendectomy: Analysis of the American Gut Project

Adults born by cesarean section appear to have a distinctly different composition of their fecal microbial population. Whether this distinction was acquired during birth, and whether it affects risk of disease during adulthood, are unknown.

Prenatal and early postnatal exposures and events can affect the entire life course. As one example, cesarean birth has been associated with an increased likelihood of asthma and cardiovascular disease in children (Renz-Polster et al., 2005, Thavagnanam et al., 2008 and Friedemann et al., 2012), hypertension in young adults (Horta et al., 2013), and obesity in both children and adults (Pei et al., 2014, Darmasseelane et al., 2014,Blustein et al., 2013 and Mueller et al., 2014). ... As well summarized by Arrieta and colleagues, several studies have noted differences in the neonatal fecal microbiota by route of delivery (Arrieta et al., 2014). ... More recently, with comprehensive analysis based on next generation sequencing of 16S rRNA genes, Dominguez-Bello and colleagues reported that route of delivery was associated with differences in the composition of the microbial populations that initially colonized the offspring. Notably, neonates who were born vaginally were colonized by vagina-associated bacteria, whereas those born by cesarean section were initially colonized by skin-associated bacteria ( Dominguez-Bello et al., 2010).

Early life alteration of the gut microbiota may have a lasting effect. Trasande et al. observed that exposure to antibiotics up to age 6 months was associated with elevated body mass index (BMI) up to age 7 years (Trasande et al., 2013).

The 16S rRNA V4 region was sequenced by the American Gut Project....Of the 1097 participants, cesarean birth was reported as “yes” by 92, “no” by 948, and missing or uncertain by 57. Likewise, appendectomy was reported as “yes” by 155, “no” by 961, and missing or uncertain by 21.

This analysis was primarily motivated by the observation that the composition of the microbiome of neonates differed significantly between those born vaginally and those born by cesarean section (Arrieta et al., 2014 and Dominguez-Bello et al., 2010). With vaginal delivery, the neonatal microbiome resembled the vaginal microbiome, with high relative abundance of Prevotella and especially Lactobacillus taxa. In contrast, cesarean-delivered neonates had a diverse array of taxa resembling the skin microbial community, including Staphylococcus, Streptococcus, Propionibacterineae, Haemophilus, and Acinetobacter ( Dominguez-Bello et al., 2010). Cesarean-delivered neonates and infants typically have a paucity of Bifidobacterium and Bacteroides species ( Arrieta et al., 2014).

In the current analysis, we observed that the fecal microbiome composition differed in adults who reported that they had been delivered by cesarean section. This suggests that a difference by route of delivery may persist into adulthood. Of the taxa noted to be increased in cesarean-delivered neonates and infants ( Arrieta et al., 2014, Penders et al., 2006 and Dominguez-Bello et al., 2010), only Haemophilus and certain Clostridia genera had elevated abundance in the fecal microbiome of cesarean-delivered adults ( Table 3).

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The studies are adding up that phthalates are harmful to humans of all ages, but uniquely so to the developing fetus. Boys exposed to high levels of phthalates before birth may have slightly altered genitals, specifically a shortened anogenital distance (the length between the anus and the genitals). This is concerning because in adulthood, this is associated with reduced semen quality and lower fertility in males - and considered a sign of incomplete masculinization. So try to avoid or lower exposure to phthalates during pregnancy (see posts on ENDOCRINE DISRUPTORS). From Environmental Health Perspectives:

Plastics chemical linked to changes in baby boys' genitals

Boys exposed in the womb to high levels of a chemical found in vinyl products are born with slightly altered genital development, according to research published today.The study of nearly 200 Swedish babies is the first to link the chemical di-isononyl phthalate (DiNP) to changes in the development of the human male reproductive tract.

Previous studies of baby boys in three countries found that a similar plastics chemical, DEHP, was associated with the same type of changes in their genitalia. Less is known about the reproductive risks of DiNP, a chemical which scientists say may be replacing DEHP in many products such as vinyl toys, flooring and packaging. In mice, high levels block testosterone and alter testicular development.

“Our data suggest that this substitute phthalate may not be safer than the chemical it is replacing,” wrote the researchers, led by Carl-Gustaf Bornehag at Sweden’s Karlstad University, in the journal Environmental Health Perspectives. Levels of DiNP in U.S. adults and children have more than doubled in the past decade.

The researchers measured metabolites of five phthalates in the urine of pregnant women during the first trimester. Development of male reproductive organs begins during that period, said senior study author Shanna Swan, a professor of reproductive science at Mount Sinai Hospital in New York. The researchers then measured the anogenital distance – the length between the anus and the genitals – when the boys were on average 21 months old. Boys who had been exposed to the highest levels of DiNP in the womb averaged a distance that was slightly shorter – about seven-hundredths of an inch – than the boys with the lowest exposures. “These were really subtle changes,” Swan said.

Considered a sign of incomplete masculinization, shortened anogenital distance in men has been associated with abnormal testicular development and reduced semen quality and fertility. In men, this measurement is typically 50 to 100 percent longer than in women. But it’s unknown whether a slightly shorter distance in infants corresponds with any fertility problems later in life.

For other phthalates, the study found shorter anogenital distance with higher concentrations, but the findings were not statistically significant, meaning they may have been due to chance. The Swedish women in the new study had phthalate levels similar to U.S. women in Swan's previous studies. Those studies, published in 2005 and 2008, linked several phthalates to shorter anogenital distance.

The scientists said exposures to the chemical can come from food or through skin contact with home furnishings or child-care articles. In 2008, the United States temporarily banned use of DiNP and two other phthalate plasticizers in toys and other children's products.... While it’s nearly impossible to eliminate exposure to phthalates, Swan suggested that pregnant women may be able to reduce their exposures by incorporating unprocessed, unpackaged foods into the diet and by avoiding heating or storing foods in plastic containers.

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Some recent research on sperm quality and implications for fertility. All from Science Daily:

Exposure to aluminum may impact on male fertility, research suggests

Research from scientists in the UK and France suggests that human exposure to aluminum may be a significant factor in falling sperm counts and reduced male fertility.Fluorescence microscopy using an aluminum-specific stain confirmed the presence of aluminum in semen and showed aluminum inside individual sperm.And the team of scientists, at the universities of Lyon and Saint-Etienne in France and Keele in the UK, found that the higher the aluminum, the lower sperm count.

Professor Exley said: "There has been a significant decline in male fertility, including sperm count, throughout the developed world over the past several decades and previous research has linked this to environmental factors such as endocrine disruptors"..."Human exposure to aluminum has increased significantly over the same time period and our observation of significant contamination of male semen by aluminum must implicate aluminum as a potential contributor to these changes in reproductive fertility."

Stress degrades sperm quality, study shows

Psychological stress is harmful to sperm and semen quality, affecting its concentration, appearance, and ability to fertilize an egg, according to a study. It is not fully understood how stress affects semen quality. It may trigger the release of steroid hormones called glucocorticoids, which in turn could blunt levels of testosterone and sperm production. Another possibility is oxidative stress, which has been shown to affect semen quality and fertility.

Twenty hours of TV a week linked to almost half sperm count of those who watch little TV

Healthy young men who watch TV for more than 20 hours a week have almost half the sperm count of men who watch very little TV, indicates a new study.

Cell phones negatively affect male fertility, new study suggests

Men who keep a cell phone in their pant pocket could be inadvertently damaging their chances of becoming a father, according to a new study. Previous research has suggested that radio-frequency electromagnetic radiation (RF-EMR) emitted by the devices can have a detrimental effect on male fertility. Most of the global adult population own mobile phones, and around 14% of couples in high and middle income countries have difficulty conceiving.

In control groups, 50-85% of sperm have normal movement. The researchers found this proportion fell by an average of 8 percentage points when there was exposure to mobile phones. Similar effects were seen for sperm viability. The effects on sperm concentration were less clear. 

Moderate weekly alcohol intake linked to poorer sperm quality in healthy young men

Moderate alcohol intake of at least 5 units every week is linked to poorer sperm quality in otherwise healthy young men, suggests research. And the higher the weekly tally of units, the worse the sperm quality seems to be, the findings indicate, prompting the researchers to suggest that young men should be advised to steer clear of habitual drinking.

Sperm size, shape in young men affected by cannabis use

Young men who use cannabis may be putting their fertility at risk by inadvertently affecting the size and shape of their sperm, according to new research. In the world's largest study to investigate how common lifestyle factors influence the size and shape of sperm, a research team found that sperm size and shape was worse in samples ejaculated in the summer months, but was better in men who had abstained from sexual activity for more than six days.