A research study out of the Karolinska Institutet has found that infants born with lower than average birth weight may be at increased risk for developing asthma later in life. The study is based on the evaluation of more than 10,000 twins in the Swedish Twin Registry.

Information on fetal growth and childhood diseases were collected from 9 year old and 12 year old sets of twins. This information was compared to the medical birth registry in Sweden. The registry records all birth information including the weight of the babies at birth and the gestational age of the pregnancy. Twins were used because both babies underwent the same conditions in utero. The twins in the study were discordant which meant only one twin had asthma.

The researchers found a relationship between the weight of the baby, or fetal growth when born and the development of asthma in childhood. "Our study shows that there's a distinct correlation between fetal growth and asthma that is independent of gestational age and environmental or genetic factors," says Catarina Almqvist Malmros. Catarina Almqvist Malmros is a pediatrician at the Karolinska Institutet.

The World Health Organization estimates more than 300 million people currently have asthma. Asthma is also the most prolific chronic disease in childhood. Over the last several decades, the number of children presenting with asthma has risen dramatically. This rise seems to be parallel to the rise in babies being born at lower than average birth weights.

Furthermore, the study reveals an implied connection between fetal growth, lung development and possible effects of malnutrition in utero. Lung development is one of the major concerns when premature babies are born. This study did not reveal whether any of the children were born prematurely, just that they were born at a low birth weight.

Source: Pediatrics - September 2009

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