Monday, June 02, 2008

Low Birth Weight May Increase Autism Risk in Girls

Low Birthweight and Advancing Paternal Age

Research and Practice
Paternal Age as a Risk Factor for Low Birthweight
Nancy E. Reichman 1* Julien O. Teitler 2

AJPH First Look, published online ahead of print March 29, 2006

American Journal of Public Health, 10.2105/AJPH.2005.066324

1 Robert Wood Johnson Medical School
2 Columbia University

Objectives. We examined associations between paternal age and low birthweight in the US urban population.

Methods. Using a population-based sample of 4621 births, we used multiple logistic regression analysis to estimate associations between paternal age and low birthweight, controlling for maternal age, other demographic factors, and the child's gender.

Results. When the child’s gender and the mother's race/ethnicity, birthplace, parity, marital status, and health insurance type were controlled, teenaged fathers were 20% less likely and fathers older than 34 years were 90% more likely than fathers aged 20 to 34 years to have low-birthweight babies. The associations were significant when maternal age was also controlled. No racial/ethnic differences in associations between paternal age and low birthweight were found.

Conclusions. We identified paternal age as an independent risk factor for low birthweight in the US urban population, suggesting that more attention needs to be paid to paternal influences on birth outcomes and to the interactive effects of urban environments and individual risk factors on health.

Key Words: Birth Outcomes, Socioeconomic Factors
Labels: advancing paternal age, autism, low birth weight, schizophrenia

Low Birth Weight May Increase Autism Risk in Girls (Update1)

By Elizabeth Lopatto

June 2 (Bloomberg) -- Autism strikes low birth weight baby girls at a higher rate than similar-sized boys when the infants are compared with larger children, according to a study that suggests risk factors for the disorder vary by sex.

Baby girls weighing less than 2.5 kilograms, or about 5.5 pounds, had 3.5 times increased risk of autism and baby girls born more than seven weeks early had a 5.4 times increased risk. Boys born small or early didn't have a significant difference in their risk of being autistic, the according to a report in the journal Pediatrics.

Doctors aren't sure what causes autism, though genetics and the environment probably both play roles, according to the National Institutes of Health. This research indicates that boys and girls have different risk factors for the disorder, said study author Diana Schendel.

``This suggests there may be sex differences in genetic factors leading to autism,'' said Schendel, a researcher for the Centers for Disease Control and Prevention, in a May 30 telephone interview. ``Girls may need an additional insult'' before birth that could include reduced growth or premature birth.

Autism and related disorders, some of them less severe, affect about 1 in 150 U.S. children. There is no cure for the malady, in which children may refuse to engage with other people, echo words and phrases, or repeat actions many times. Risk factors include older fathers and environmental toxins.

About 1 in 13 babies in the U.S. has low birth weight, according to the March of Dimes. Babies may weigh less than 5 pounds 8 ounces because they're premature, because the mother has heart problems, because of infections or because of cigarette, drug, or alcohol use.

`Biggest Risk Factors'

``We know that low birth weight and pre-term birth are among the biggest risk factors for developmental disabilities,'' Schendel said. ``The higher prevalence of autism supports monitoring these children carefully for behavioral problems.''

Babies born with low birth weights are likelier to have bleeding in the brain, lungs that are more likely to collapse, heart problems, and vision loss.

The study was of children born from 1981 to 1993 in Atlanta, who lived to 3 years of age, and were still living in Atlanta at ages 3 to 10. Over 550 children with autism were paired to normal children born in the same year.

To contact the reporter on this story: Elizabeth Lopatto in New York at



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