February 2nd, 2010 
A common complication during pregnancy may predispose children born prematurely to asthma, a large study reports today.
The condition, chorioamnionitis, is inflammation of the fetal membranes and amniotic fluid from a bacterial infection. It is thought to be linked to more than half of all preterm births, before 37 weeks’ gestation, scientists write in today’s Archives of Pediatric and Adolescent Medicine.
The infection may have ascended to the uterus from the mother’s genital tract or traveled through her bloodstream from a more remote site, such as her gums or upper respiratory tract, says lead author Darios Getahun, a scientist at Kaiser Permanente Southern California’s Department of Research and Evaluation in Pasadena.
In animals, chorioamnionitis has been shown to cause lung and brain damage in offspring, Getahun says. Scientists also have found lung scarring in infants who died after pregnancies complicated by the condition.
Getahun and his co-authors analyzed electronic health records for all singleton children born at Kaiser’s Southern California hospitals in 1991 to 2007, a total of 397,852. Of those, 28,869 were preterm.
Among children born full-term, chorioamnionitis wasn’t linked to an increased risk of being diagnosed with asthma by age 8. But among those born prematurely, the condition was associated with double the risk of childhood asthma in blacks, a 70% increase in Hispanics and a 66% increase in whites. The researchers observed these differences even after accounting for other possible risk factors such as whether the mother smoked or had asthma herself. Only in Asian/Pacific Islanders preemies did chorioamnionitis not seem to make a difference in childhood asthma risk.
Getahun speculates that chorioamnionitis wasn’t related to asthma risk in full-term children because their mothers might not have had it as long as those born prematurely. But, he adds, his team didn’t have information about how early in their pregnancy women were diagnosed.
Diagnosing the condition is tricky, Getahun says, because symptoms — fever in the mother, tenderness or pain in the uterus, foul-smelling amniotic fluid — aren’t definitive, and some women never exhibit symptoms. Getahun’s team is now trying to find a marker in the mother’s blood that would signify her symptoms are because of chorioamnionitis.
A study of 1,096 children published in 2008 found a higher risk of wheezing by age 2 in preemies whose mothers had had chorioamnionitis.
Related
- Neglecting Asthma Treatment During Pregnancy Increases Risk of Asthma in Child
Expectant mothers who eschew asthma treatment during pregnancy heighten the risk transmitting the condition to their offspring, according to one of the largest studies of its kind published in the European Respiratory Journal.
A research team from the Université de Montréal, the Hôpital du Sacré-Cœur de Montréal and Sainte-Justine University Hospital Research Center found that 32.6 percent of children born to mothers who neglected to treat their asthma during pregnancy developed the respiratory illness themselves.
“Uncontrolled maternal asthma during pregnancy could trigger a transient yet important reaction in the fetus that affects lung development and could subsequently increase the likelihood of a baby developing asthma in later childhood,” warns lead author Dr. Lucie Blais, a professor at the Université de Montréal’s Faculty of Pharmacy and researcher at the Hôpital du Sacré-Cœur de Montréal.
As part of the study, the research team examined a decade of health records for 8,226 children – from birth to 10 years of age – born to asthmatic mothers. Parents of these children were also mailed questionnaires requesting additional facts concerning familial medical history, lifestyle habits and environment.
“We found that failing to control maternal asthma during pregnancy clearly has an impact on asthma in offspring – a consequence that is independent of other contributing factors,” says Dr. Blais. “It is of great importance for physicians to adequately treat asthmatic mothers during pregnancy, not only for the favourable outcome of pregnancy but also for the benefit of the child.”
- Delay Pregnancy to Avoid Repeat Premature Rupture of Membranes
Women whose water has broken early may want to wait at least 18 months before having their next child, new research shows.
Known by doctors as preterm premature rupture of membranes, this complication, in which a woman’s water breaks before her pregnancy has reached full term and before labor has begun, occurs in up to 5 percent of pregnancies, Dr. Darios Getahun of Kaiser Permanente Southern California Medical Group in Pasadena and colleagues note in their report.
The complication accounts for one in every four premature births, they report in the American Journal of Obstetrics & Gynecology, and puts mother and fetus at risk of infection.
While the reasons why some women’s water breaks early are “elusive,” Getahun and his team say, there are likely many factors involved. Women who have had the complication previously, they add, are known to be at greater risk in subsequent pregnancies. And the risk is also known to be higher for black women compared to whites.
To investigate whether the length of time between pregnancies might also influence this risk, the researchers reviewed data from the state of Missouri on nearly 200,000 women who had two or three children between 1989 and 1997. Around 3 percent of black women and 1 percent of white women’s water broke early during their first or second pregnancies.
Among white women whose water broke early, 6 percent had the complication in their subsequent pregnancy, compared to 2 percent of women who hadn’t suffered premature membrane rupture.
The rates for black women were 10 percent and 4 percent, respectively. This translated to a nearly nine-fold increased risk of subsequent early water breaking for white women, and a seven-fold greater risk for black women.
The risk was even further increased if a woman got pregnant again within 18 months, and was particularly high for African-American women. For example, a black woman who got pregnant again within three to six months would be nearly nine times more likely to have the complication than a woman who waited at least 18 months.
The risk of early water breaking for white women who got pregnant again this soon was tripled.
This suggests, the researchers say, that the complication may be related to inflammation, and that a longer interval between pregnancies is needed to allow for full recovery. “We think that it might be a chronic inflammation that may persist from one pregnancy to another pregnancy,” Getahun told Reuters Health.
Women whose water has broken early should be watched closely in subsequent pregnancies, he added, so that if infection does develop they can receive prompt antibiotic treatment, which could help prevent the complication from recurring.
- Smoking pregnant increases baby’s asthma risk: study
Smoking during pregancy increases the risk of a baby developing asthma up to sixfold, said a Swedish study published at the European Respiratory Society’s annual congress on Monday.
The study by Professeur Anders Bjerg of the Sunderby central hospital in Norrbotten and his specialists showed that smoking leads to babies being born underweight, a fact that has an impact on the development of asthma.
The Swedish doctors studied asthma in about 3,400 children between 1996 and 2008.
The study found that babies of smoking mothers had an average weight of 211 grammes (7.44 ounces) less than those of mothers who do not smoke.
Nearly a quarter (24.3 percent) of smoking mothers’ babies weighed less than 2.5 kilogrammes at birth against 4.1 percent for those of non-smoking women.
In underweight children of women who smoked throughout their pregnancy the asthma risk was at 23.5 percent, against 7.7 percent in children of non-smoking mothers who were born with an average weight.
- Use of Acetaminophen in Pregnancy Associated With Increased Asthma Symptoms in Children
Children who were exposed to acetaminophen prenatally were more likely to have asthma symptoms at age five in a study of 300 African-American and Dominican Republic children living in New York City. Building on prior research showing an association between both prenatal and postnatal acetaminophen and asthma, this is the first study to demonstrate a direct link between asthma and an ability to detoxify foreign substances in the body. The findings were published this week in the journal Thorax.
The study, conducted by the Columbia Center for Children’s Environmental Health at Columbia University’s Mailman School of Public Health, found that the relationship was stronger in children with a variant of a gene, glutathione S transferase, involved in detoxification of foreign substances. The variant is common among African-American and Hispanic populations. The results suggest that less efficient detoxification is a mechanism in the association between acetaminophen and asthma.
The researchers assessed the use of analgesics during pregnancy and found that 34 percent of mothers reported acetaminophen use during pregnancy, and 27 percent of children had wheeze, an asthma-related symptom. The children whose mothers had taken acetaminophen were more likely to wheeze, visit the emergency room for respiratory problems, and develop allergy symptoms, compared to those children whose mothers did not take acetaminophen. The risk increased with increasing number of days of prenatal acetaminophen use. The children in this study live in neighborhoods of New York City that have been the hardest hit by the asthma epidemic: Northern Manhattan and the South Bronx.
Acetaminophen use among children in the U.S. has increased substantially since the early 1980s and has become increasingly common among women during pregnancy so that most women in the U.S. take acetaminophen during pregnancy. This increase coincided with a doubling of the prevalence of asthma among children in the country between 1980 and 1995.
“These findings might provide an explanation for some of the increased asthma risk in minority communities and suggest caution in the use of acetaminophen in pregnancy,” says Matthew S. Perzanowski, PhD, assistant professor of Environmental Health Sciences at the Mailman School of Public Health.
Reasons for prenatal acetaminophen use vary, but in this study population the observed associations with headaches suggest pain management as likely; however, other host factors that caused mothers to take acetaminophen and also cause asthma may explain their association. While infection is one such potential confounder, the Mailman School researchers found no association between the reported use of antibiotics and acetaminophen, and adjustment for antibiotic use during pregnancy did not affect the results.
According to the researchers, the prevalence of current wheeze diminished as the children aged, from 40 percent at age one year to 25 percent, 17 percent and 27 percent at ages two, three, and five, respectively. However, the association between prenatal acetaminophen exposure and current wheeze strengthened as the children aged.
The Columbia Center for Children’s Environmental Health study adjusted relative risks for sex, race/ethnicity, birth order, maternal asthma, maternal hardship, exposure to environmental tobacco smoke, antibiotic use and postnatal acetaminophen use.
In a similar study conducted in the UK, the frequency of acetaminophen use during pregnancy and the magnitude of association in the UK study were similar to that in New York City.
- Birth defects in babies linked to mother’s job
Women working as scientists and pharmacists run a greater risk of having babies with birth defects as compared to women in other professions, suggests a new study by the New York State Department of Health.
The study, published in the journal Occupational and Environmental Medicine, involved 8,977 cases of birth defects and 3,833 healthy controls from the National Birth Defects Prevention Study.
On analyzing mothers of around 9,000 children with birth defects, the researchers observed that certain abnormal birth conditions were more likely to be found in children of janitors, pharmacists or biological and chemical scientists.
“Given those job titles, one would expect those women to work with different chemicals or something that could possibly be an exposure,” said lead author Michele Herdt-Losavio from the New York State Department of Health.
Depending on the profession of the mother, the baby could be born with any of the physical defects, which are not related to the DNA, found Dr. Herdt-Losavio and her colleagues after studying 45 specific birth defects among mothers with 24 different occupations.
Women working as janitors were found to be more likely to give birth to a child with one or more of the defects including ear and eye defects, musculoskeletal problems, gastrointestinal problems, oral clefts and various other defects.
However, not all women working as janitors face similar risks, as Dr. Herdt-Losavio said, “There’s lots of questions that can be asked…. What do you do as a janitor? What products do you use? What hours do you work? How many hours do you work?”
The researchers, however, did not probe the probable reasons for this association between the birth defect of a child and his mother’s profession but they did offer a possible reasoning.
“What we can guess by looking at these job titles is that … it’s possible that they work with chemicals,” said Dr. Herdt-Losavio. “It’s not possible to say what those chemicals might be, or how much they might work with. But what we can do is point other [researchers] in the direction and give them some idea of where they might want to dig further and collect more data.”
