Low Birth Weight, Preterm Birth Increases Autism Risk

Low birth weight and preterm birth increase the risk for children developing autism later in life.

A team of researchers from National Center on Birth Defects and Developmental Disabilities examined 565 children with autism born between 1986 and 1993. Researchers also considered a control group of children with similar dates of birth. The study examined and compared the link between birth weight, birth date, and autism.

Researchers estimated low birth weight as less than 5.5 pounds, and preterm birth as less than 33 weeks' gestation.

Children with autism were then divided into three groups: children with autism only, children with autism and one developmental disease, and children with autism and more than one developmental disease.

The study found that both low birth weight and preterm birth differently affect autism risk. The combination and the levels of these two factors determine the risk of a child for developing autism and possibly over developmental disease as well, called 'autism spectrum'.

Birth weight less than 5.5 pounds increases risk for autism in both boys and girls by 2.3 times in average. However, the risk varies for sexes: low birth weight girls were 4 times more likely to develop autism and mental retardation together, but boys did not show to be at an increased risk because of low birth weight. Preterm birth less than 33 weeks' gestation doesn't significantly affect autism risk in boys, but it increases the risk in girls.

The study comes with a surprise for researchers, because autism mainly affects boys. This study shows that both factors low birth weight and preterm birth mostly affect baby girls.

The study is yet unable to explain why the link occurs. It is unknown whether brain damage occurs later in life because of low birth weight and preterm birth or brain damage occurs in a fetus in mother's womb and then leads to abnormal body development. However, the link is more than clear urging the need of healthy pregnancy and close monitoring of low birth weight children for developmental diseases.

The research suggests that those with low birth weight and preterm birth must be regularly checked for autism and other developmental problems at 18, 24, and 30 months. These children are already being closely monitored for other diseases, because they are at high risk, but researchers suggest that autism check-ups need special attention.