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Accelerated infant growth increases risk of future asthma symptoms in children

30 Jan 2012

Accelerated growth in the first three months of life, but not fetal growth, is associated with an increased risk of asthma symptoms in young children, according to a new study from The Generation R Study Group at Erasmus Medical Center in the Netherlands.

“We know that low birth weight is associated with an increased risk of asthma symptoms in children, but the effects of specific fetal and infant growth patterns on this risk had not been examined yet,” said researcher Liesbeth Duijts, MD, PhD. “In our study, weight gain acceleration in early infancy was associated with an increased risk of asthma symptoms in children of preschool age, independent of fetal growth patterns, suggesting that early infancy might be a critical period for the development of asthma.”

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The findings were published online ahead of print publication in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine.

This study was embedded in the Generation R Study, a population-based prospective cohort study, and included 5,125 children who were followed from fetal life through the age of four. Information on asthma symptoms was obtained by questionnaires at the ages of 1, 2, 3, and 4.

No consistent relationships between fetal length and weight growth during different trimesters and the development of asthma symptoms were observed. Accelerated weight gain from birth to 3 months following normal fetal growth was associated with increased risks of asthma symptoms, including wheezing (overall odds ratio (OR) 1.44 (95% confidence interval (CI): 1.22, 1.70), shortness of breath: 1.32 (1.12, 1.56), dry cough: 1.16 (1.01, 1.34), and persistent phlegm: 1.30 (1.07, 1.58)). The associations between accelerated infant growth and risk of developing asthma symptoms were independent of other fetal growth patterns and tended to be stronger among children of atopic mothers.

“Our results suggest that the relationship between infant weight gain and asthma symptoms is not due to the accelerated growth of fetal growth-restricted infants only,” said Dr. Duijts. “While the mechanisms underlying this relationship are unclear, accelerated weight growth in early life might adversely affect lung growth and might be associated with adverse changes in the immune system.”

The study had a few limitations, including the possibility of measurement error in the estimation of fetal weight and the use of self-report for asthma symptoms.

“Further research is needed to replicate our findings and explore the mechanisms that contribute to the effects of growth acceleration in infancy on respiratory health,” concluded Dr. Duijts. “The effects of infant growth patterns on asthma phenotypes in later life should also be examined.”

Exposure to chemical found in personal care products may contribute to childhood obesity

Researchers from the Children’s Environmental Health Center at The Mount Sinai Medical Center in New York have found an association between exposure to the chemical group known as phthalates and obesity in young children – including increased body mass index (BMI) and waist circumference.

Phthalates are man-made, endocrine-disrupting chemicals that can mimic the body’s natural hormones. They are commonly used in plastic flooring and wall coverings, food processing materials, medical devices, and personal-care products. While poor nutrition and physical inactivity are known to contribute to obesity, a growing body of research suggests that environmental chemicals – including phthalates – could play a role in rising childhood obesity rates.

This study was the first to examine the relationship between phthalate exposure and measurements used to identify obesity in children. The paper is available online in the journal Environmental Research. The project was funded by the National Institute for Environmental Health Sciences, the National Cancer Institute, and the U.S. Environmental Protection Agency.

Mount Sinai researchers measured phthalate concentrations in the urine of 387 black and Hispanic children in New York City, and recorded body measurements including BMI, height, and waist circumference one year later. The urine tests revealed that greater than 97 percent of study participants had been exposed to phthalates typically found in personal care products such as perfume, lotions, and cosmetics; varnishes; and medication or nutritional supplement coatings. The phthalates included monoethyl phthalate (MEP) and other low molecular-weight phthalates. The team also found an association between concentrations of these phthalates with BMI and waist circumference among overweight children. For example, BMI in overweight girls with the highest exposure to MEP was 10 percent higher than those with the lowest MEP exposure.

“Research has shown that exposure to these everyday chemicals may impair childhood neurodevelopment, but this is the first evidence demonstrating that they may contribute to childhood obesity,” said the study’s lead author Susan Teitelbaum, PhD, Associate Professor in the Department of Preventive Medicine at Mount Sinai School of Medicine. “This study also further emphasizes the importance of reducing exposure to these chemicals where possible.”

The percentage of obese children ages six to 11 in the United States has grown from seven percent in 1980 to more than 40 percent in 2008, according to the U.S. Centers for Disease Control and Prevention. More than 15 percent of American children between the ages six and 19 are characterized as obese. In New York City, more than one in five children in public schools are obese.

Dr. Teitelbaum and the team at the Children’s Environmental Health Center plan to further evaluate the impact of these chemicals on childhood obesity. “While the data are significant, more research is needed to definitively determine whether phthalate exposure causes increases in body size,” she said.

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