From Mama’s Achoo! to Baby’s Asthma

Pollen exposure in pregnancy might lead to babies at risk for asthma

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Is stopping to smell the roses a bad idea if you’re eight months pregnant? One rose too many might not be advised.

A recent study found that women who were exposed to high levels of pollen late in their pregnancies had a higher chance of having a baby with asthma symptoms in their first year of life.

"Consult a pediatrician if your child has asthma symptoms."

Adrian Lowe, PhD, MPH, of the Department of Public Health and Clinical Medicine at Umeå University in Sweden, and colleagues led the study to look at the relationship between how much pollen a pregnant woman is exposed to in various stages of her pregnancy and the likelihood that her baby will develop asthma.

To conduct the study, researchers used records from several different sources.

They obtained birth and health information from Sweden’s national birth and health registry. The researchers used the records for 110,381 babies delivered in Stockholm between 1989 and 1996.

The records included information about date of birth, which pregnancy this was for the mother, birth weight and length, gestational age, infant gender and smoking habits of the mother during pregnancy.

The researchers got information about daily pollen measurements from records at the Swedish Museum of Natural History. For each of the infants in their database, the researchers determined the average amount of pollen in the air during the first 12 weeks and last 12 weeks of each mother’s pregnancy, as well as the first 12 weeks of each child's infancy.

Pollution measurements were obtained from the City of Stockholm Environment and Health Administration. For each child, researchers calculated the average pollution levels during the same periods as the pollen measurements.

Asthma information for each infant was collected from the Swedish Inpatient Registry. They found out if the infant had been admitted to the hospital for asthma care during their first twelve months.

The researchers also looked at how frequently each infant was admitted for lower respiratory tract illness. This was to estimate any potential exposures to infectious agents the infants might have breathed in during the first three and six months of their lives.

The data showed that in most years, the month a child was born affected their risk of being hospitalized for asthma. Children who were born from February to July had the lowest risk. Children who were born in October through November had the greatest risk.

Through their analysis, the researchers found that that children whose mothers were exposed to high levels of pollen late in their pregnancies had an increased risk of being hospitalized for asthma symptoms.

The researchers also found that children of heavily-smoking mothers who had been exposed to high pollen levels in their infancy had a reduced risk for being hospitalized for asthma symptoms. Children with non-smoking mothers did not have a reduced risk.

The researchers concluded that there needs to be more research to fully understand the connection between a pregnant woman’s pollen exposure and her child’s future asthma.

Such research could help develop treatments to reduce the risk of asthma for these babies, the authors wrote.

The study was published on November 7 in the journal Allergy, Asthma & Clinical Immunology.

The authors reported no conflicts of interest. The research was funded by the Swedish Research Council, the Australian National Health and Medical Research Council and the Centre for Environmental Research in Umeå, Sweden.

Reviewed by: 
Review Date: 
January 22, 2013
Last Updated:
August 19, 2013