Mother's prenatal stress predisposes their babies to asthma and allergy

Women who are stressed during pregnancy may pass some of that frazzlement to their fetuses in the form of increased sensitivity to allergen exposure and possibly future asthma risk, according to researchers from Harvard Medical School who will present their findings at the American Thoracic Society's 2008 International Conference in Toronto on Sunday, May 18.

“While predisposition to asthma may be, in part, set at birth, the factors that may determine this are not strictly genetic. Certain substances in the environment that cause allergies, such as dust mites, can increase a child's chance of developing asthma and the effects may begin before birth,” said Rosalind J. Wright, M.D., M.P.H., assistant professor of medicine at Brigham & Women's Hospital and Harvard Medical School .

Mother's stress during pregnancy can also influence the babies developing immune system. While animal studies suggest that the combination of stress and allergen exposure during pregnancy may magnify the effects on the immune system, this is the first human study to examine this directly. The researchers analyzed levels of maternal stress and mother's exposure to dust mite allergen in their homes while pregnant with respect to cord blood IgE expression—a marker of the child's immune response at birth— in 387 infants enrolled in the Asthma Coalition on Community, Environment, and Social Stress (ACCESS) project in Boston .

They found increased levels of IgE expression in cord blood among infants whose mothers experienced higher level stress even when exposed to relatively low levels of dust mite during pregnancy. This indicates that mother's stress during pregnancy magnified the effect of dust exposure on the child's immune system such that the child's immune response at birth may be altered even with lower levels of dust exposure in the home. The results held true regardless of the mother's race, class, education or smoking history.

“This research adds to a growing body of evidence that links maternal stress such as that precipitated by financial problems or relationship issues, to changes in children's developing immune systems, even during pregnancy,” said Dr. Wright. “This further supports the notion that stress can be thought of as a social pollutant that, when ‘breathed' into the body, may influence the body's immune response similar to the effects of physical pollutants like allergens, thus adding to their effects.”

While these findings are important, Dr. Wright noted that only with continued follow-up of these children will they know if these effects will result in increased asthma risk. Moreover, it will be important to replicate these findings in larger populations to give a clearer picture of the relationship between prenatal maternal stress, allergen exposure and subsequent childhood asthma development.

“It is notable that these findings were obtained in a U.S. urban population, which may be more likely to be simultaneously exposed to multiple factors, including stress and indoor allergens. More studies like this may help explain why asthma occurs more frequently in these high-risk groups,” said Junenette Peters, Sc.D., postdoctoral research fellow who presented these results.

In the meantime, the findings suggest that when such exposures—prenatal stress, allergen exposure— occur together, there is a magnified increase in risk, which supports the assessment of maternal psychological well-being along with other environmental factors as part of a prenatal health program.

Mom's Stress in Pregnancy May Up Baby's Asthma and Allergy Risk

If an expectant mother is exposed to high levels of stress, her baby may be more likely to develop asthma or allergies later in life, new research suggests.

Babies born to mothers experiencing high levels of stress had more IgE in their blood at birth than did babies born to less-stressed moms. IgE is an antibody involved in allergic and asthmatic reactions.

"Moms who had elevated levels of stress had children who seemed to be more reactive to allergens, even when exposed to low levels of allergens," said study co-author Dr. Rosalind Wright, an assistant professor of medicine at Brigham and Women's Hospital and Harvard Medical School in Boston .

Wright's colleague, and another author of the study, Junenette Peters, said that stress may make women more susceptible to allergens because it "may make the cells more permeable" so that even low levels of exposure trigger a reaction. And, women whose immune systems are altered by stress may, in turn, pass down that trait to their infants.

Peters, a postdoctoral research fellow at Harvard Medical School , was to present the findings Sunday at the American Thoracic Society's 2008 International Conference, in Toronto .

The study, which was funded by a grant from the U.S. National Heart, Lung, and Blood Institute, included 315 expectant mothers and their infants. All of the mothers lived in an urban environment.

Mothers filled out a questionnaire designed to assess their levels of stress in many different domains. Financial issues, home issues, community safety, relationship problems and medical issues were the most frequently reported negative events experienced by the mothers.

Dust mite exposure was also assessed using samples obtained from the pregnant women's bedrooms. When the babies were born, a sample of cord blood was taken.

After controlling the data to compensate for maternal age, race, smoking, education, history of allergy and asthma, the child's gender and the season of birth, the researchers found that the number of negative domains -- stressors -- reported was associated with an increased risk of elevated IgE in the cord blood.

"A mom who had three or more negative events would have a 12 percent increased chance of having a baby with elevated cord blood IgE," Peters said.

Wright pointed out that elevated IgE is "suggestive" of an increased risk of developing asthma and allergy later in life, but that the association isn't clear-cut and likely depends on exposure to other risk factors. The researchers will be following these children until they're 5 years old to see if they end up developing asthma and allergies later in life.

Dr. Ashlesha Dayal is a maternal fetal medicine specialist at Montefiore Medical Center , and an assistant professor of obstetrics and gynecology at Albert Einstein Medical College in New York City . She said: "There's definitely emerging data that stress in pregnancy can affect the pregnancy in different ways; for example, stress has been linked to growth restriction, decreased bonding, and even preterm delivery. So, it wouldn't be unreasonable to think that it would precipitate a disease that's triggered by stress."

But, added Dayal, "This is a small study that needs to be validated. We really need more numbers to verify this association."

Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital in Detroit , agreed. "This is an interesting study, but it hasn't demonstrated cause and effect. Maybe what goes on before birth can have long-lasting effects," she said, but added that she doesn't think this is something expectant mothers needed to be overly concerned about in most cases.

Wright said that, although the researchers aren't making specific recommendations on stress reduction based on this study, for your general well-being, it's a good idea to reduce your stress levels whenever possible.

Asthma Research Reveals Baby’s Immunity Affected by Mom’s Stress

Pregnant mothers who are subjected to stressors increase their babies' risk of developing asthma and various allergic reactions.

Harvard Medical School researchers, while studying the correlation of maternal stress to asthma risks on children in a given population group, came up with the finding.

Immunologic response, as revealed by measuring the levels of antibodies in the blood, reveal that mothers exposed to high-level stress during the gestation period gave birth to babies with higher susceptibility to allergic reactions.

The correlation, even in cases with comparatively lower contact to substances which trigger allergic reactions and asthma of the mother during pregnancy, was still present.

A child's natural resistance is shaped by the pregnant mother's exposure to stressors, information presented in Toronto in 2008 during the American Thoracic Society's International Conference.

Rosalind J. Wright, MD, MPH states that, however, it is too early to conclude that maternal stress contributes to ulterior asthma risks, since the studied children are still too young anyway to show signs of asthma.

Some of those that were included in the study are still in utero, whereas the eldest participants are only 4 years old.

Wright also states that further developments to the study will occur only when the children reach around 3 to 5 years of age.

Economic Conditions Linked to Asthma around 1 in 10 children in the U.S. is asthmatic. The rates for Afro-American and Hispanic children, as reported, are even greater.

Between kids living in higher economic status and kids in lower economic status, the latter's rate for developing asthma is nearly twice as high. One of the considered risk factor for asthma is poverty.

For this reason, Wright's team came up with the Asthma Coalition on Community, Environment and Social Stress (ACCESS), aiming to probe the relationship between asthma and a targeted population group.

Wright adds that some environmental substances, like dust and dust-house mites, act as allergens that can increase the child's risk for developing asthma. However, this is not purely genetic, and the effects may even begin prior to birth.

Data was amassed from closely-monitored pregnant participants, giving birth to a total of 387 infants.

Surveys revealed the amount of stressors experienced by the mothers during gestation, while ocular inspection of the surroundings measured their exposure to allergens.

Immunoglobulin E (IgE), a natural antibody, was measured. Blood samples were taken in the umbilical cord at birth.

Ige Levels Increased with Stress Despite exposure to low levels of allergens, like house-dust mites, research revealed that IgE levels in the blood of infants is significantly increased; those infants whose mothers were exposed to high-level stress during their gestational period.

Stressors were brought about mostly by economic factors such as finances and the community in general.

Jeanette Peters, PhD states that IgE levels revealed an alteration in the affected child's defense system. Pregnant women who lived through at least three stressful instances had a 12% more risk of having their children affected.

Pregnant mothers, who had the most stress experienced and exposure to house-dust mites, gave birth to babies with the highest IgE measurement in their blood levels.

To improve findings on the correlation of asthma to maternal stress and environmental agents such as house-dust mites, the children will be studied until they reach 5 to 6 years of age.

There is already, however, an imperative public health message awareness brought about by the research, even this early a time.

Peters says that the factors contributing to the child's predisposition to asthma--both the high-level stress and exposure to environmental allergens such as house-dust mites--could still have a significant effect on the immune system, even when the latter is greatly reduced.

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