Study: Link between preterm birth and autism

A study indicates that premature infants could be at an increased risk of developing autism.

According to a new study, very premature infants may have an increased risk of being diagnosed with autism by age 4, although the research questions just how high the odds are.

The Australian study, published online Jan. 21 in Pediatrics, found that just under 2 percent of tiny preemies were later diagnosed with autism between 2 and 4 years of age.

That prevalence, the researchers say, is lower than what's been seen in past studies -- where figures have ranged from roughly 4 percent to 13 percent.

They also said there are reasons to trust the reliability of their findings. This study is one of the few to directly evaluate children, rather than using parent questionnaires, said lead researcher Margo Pritchard, a professor of neonatal nursing at Australian Catholic University, in South Brisbane.

"What we found is that being born very preterm is a risk factor, which is consistent with previous studies," Pritchard said. "But when diagnostic rigor is applied, using direct assessment, the rate of autism is lower than reported in other studies."

However, Dr. Paul Wang, senior vice president of medical research for the nonprofit organization Autism Speaks, said it's not clear what to make of the lower prevalence.

Studies differ in their methods, and some have followed children for longer periods -- to age 8 and beyond -- so it's hard to know which estimates are closer to the truth, Wang said.

Instead, he saw the new findings as further support for the overall picture. "Prematurity and low birth weight are risk factors for autism," Wang said.

He also stressed, however, that there is no single contributing factor to autism spectrum disorder -- a developmental disorder thought to affect one in 68 children in the United States, according to the U.S. Centers for Disease Control and Prevention.

Autism is complex, Wang said, and the mix of causes varies from one child to the next. But in general, experts believe it starts with a genetic vulnerability, in combination with certain environmental exposures at a critical point in development -- particularly in the womb.

Researchers are still trying to understand the environmental influences, Wang said.

According to Autism Speaks, studies have implicated a number of factors other than preterm birth. Those include older age of the parents at conception, as well as prenatal exposure to certain infections, air pollution or particular medications -- such as the anti-seizure drug valproic acid (Depakote).

For the new study, Pritchard's team assessed 169 young children born before the 29th week of pregnancy. They were screened at ages 2 and 4 years for possible signs of autism -- such as language delays, or a lack of interest in other children.

Overall, 13 percent of the children screened "positive" and underwent further evaluation. In the end, just under 2 percent were diagnosed with autism.

Still, Wang pointed out, nearly all of the children who screened positive but did not get a formal diagnosis did have significant problems -- with communication, imaginative play or repetitive behavior, for example.

And since very preterm babies are at risk of various developmental problems, it can be hard to definitively diagnose autism at a young age, Wang said.

Pritchard agreed that it's challenging to pinpoint autism in those children. But, she added, "gold standard" assessments such as the Autism Diagnostic Observation Schedule -- which was used in this study -- can help identify the disorder at an early age.

Whatever the true prevalence of autism is among preemies, it's important that these children have routine developmental screenings, Wang and Pritchard said.

"These children all need to be followed closely and screened," Wang said. That way, any impairments -- physical, mental or social -- can be caught early and addressed.

"Identifying early differences in development can help to link children with effective intervention practices," Pritchard agreed.

"The take-home message," she added, "is to take advantage of developmental monitoring and keep children born very preterm on these programs through childhood."

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Reduced Risk of Preterm Birth for Pregnant Women who Received Flu Vaccination

Women who were vaccinated for H1N1 in 2009 were less likely to have their children pre-term.

Pregnant women who received the H1N1 influenza vaccine during the 2009 pandemic were less likely to have premature babies, and their babies weighed more on average.

Influenza infection during pregnancy is associated with adverse infant outcomes such as preterm birth. Emory researchers from the Rollins School of Public Health, in a joint study with Kaiser Permanente of Georgia and the Mid-Atlantic States, evaluated the effectiveness of the H1N1 influenza vaccine in pregnant women against adverse infant outcomes during the 2009 pandemic. They compared birth outcomes among pregnant women who received the vaccine to those among pregnant women who were not vaccinated.

The researchers used de-identified electronic medical records for 3,327 women enrolled in Kaiser Permanente managed care organization sites between April 2009 and April 2010. The study looked at whether women got the H1N1 influenza vaccine during pregnancy and their birth outcomes such as premature birth and birth weight. Overall findings showed that vaccinated mothers were less likely to deliver their babies prematurely. On average, infants of vaccinated mothers also weighed more at birth than infants born to unvaccinated mothers.

"Our findings confirm the importance of receiving the influenza vaccine during pregnancy in order to protect the infant's health," explains Jennifer Richards, MPH, first author of the study. "Previous studies have shown that seasonal influenza vaccination may prevent preterm birth. This study shows that moms who were vaccinated during the H1N1 pandemic were less likely to have premature babies."

Influenza infection is especially dangerous for pregnant women. It increases risk of adverse infant outcomes, and of complications such as hospitalization for flu. During the 2009 H1N1 influenza pandemic, pregnant women in the U.S. experienced higher influenza-associated morbidity and mortality in comparison to the general population. Getting the flu vaccine during pregnancy can not only help to prevent infection for the mother, but studies have shown that it also protects the fetus and infant after birth.

"There is always an understandable heightened sense of caution by pregnant women," explains senior study author Saad B. Omer, PhD, assistant professor of global health at Rollins and an affiliate investigator at Kaiser Permanente Georgia. "Getting vaccinated has proven to be the best protection. Our study supports the U.S. policy to prioritize pregnant moms to receive the influenza vaccine."

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Autistic Kids Born Preterm or Post-Term Have More Severe Symptoms

For children with autism, being born several weeks early or several weeks late tends to increase the severity of their symptoms, according to new research out of Michigan State University.

Additionally, autistic children who were born either preterm or post-term are more likely to self-injure themselves compared with autistic children born on time, revealed the study by Tammy Movsas of MSU's Department of Epidemiology.

Though the study did not uncover why there is an increase in autistic symptoms, the reasons may be tied to some of the underlying causes of why a child is born preterm (prior to 37 weeks) or post-term (after 42 weeks) in the first place.

The research appears online in theJournal of Autism and Development Disorders.

Movsas, a postdoctoral epidemiology fellow in MSU's College of Human Medicine, said the study reveals there are many different manifestations of autism spectrum disorder, a collection of developmental disorders including both autism and Asperger syndrome. It also shows the length of the mother's pregnancy is one factor affecting the severity of the disorder.

While previous research has linked premature birth to higher rates of autism, this is one of the first studies to look at the severity of the disease among autistic children who had been born early, on time and late.

"We think about autism being caused by a combination of genetic and environmental factors," she said. "With preterm and post-term babies, there is something underlying that is altering the genetic expression of autism.

"The outside environment in which a preterm baby continues to mature is very different than the environment that the baby would have experienced in utero. This change in environment may be part of the reason why there is a difference in autistic severity in this set of infants."

Movsas added that for post-term babies, the longer exposure to hormones while a baby is in utero, the higher chance of placental malfunction and the increased rate of C-section and instrument-assisted births may play a role.

The study also found that babies born outside of normal gestational age (40 weeks) -- specifically very preterm babies -- showed an increase in stereotypical autistic mannerisms.

"Normal gestation age of birth seems to mitigate the severity of autism spectrum disorder symptoms, and the types of autistic traits tend to be different depending on age at birth," she said.

The study analyzed an online database compiled by Kennedy Krieger Institute at Johns Hopkins University of nearly 4,200 mothers -- with autistic children ages 4-21 -- between 2006 and 2010. It divided the data on births into four categories: very preterm (born prior to 34 weeks); preterm (34 to 37 weeks); standard (37 to 42 weeks); and post-term (born after 42 weeks)

The mothers filled out a pair of questionnaires regarding the symptoms of their autistic children, and the results revealed very preterm, preterm and post-term autistic children had significantly higher screening scores for autism spectrum disorder than autistic children born full term.

"The findings point to the fact that although autism has a strong genetic component, something about pregnancy or the perinatal period may affect how autism manifests," said Nigel Paneth, an MSU epidemiologist who worked with Movsas on the paper. "This adds to our earlier finding that prematurity is a major risk factor for autism spectrum disorder and may help us understand if anything can be done during early life to prevent or alleviate autism spectrum disorder."

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First use of high-field MRI in developing brain reveals previously undetectable injuries

Pediatric neuroscientists at Oregon Health & Science University Doernbecher Children's Hospital are the first to use high magnetic field strength MRI to reveal tiny white matter injuries in the developing brain previously undetectable using standard MRI.

Early, accurate identification of these lesions in the preterm human infant could prevent delays in therapy and enable physicians to inform families sooner of the potential for complications. The team's findings are published in the Annals of Neurology.

White matter injury is the most common cause of chronic neurologic disability in children with cerebral palsy, explains principal investigator Stephen Back, M.D., Ph.D., but babies with cerebral palsy often have MRIs that miss injury, which creates significant challenges, including delayed treatment intervention and rehabilitation.

"Until now there hasn't been a compelling reason to put preterm babies into a high-field MRI scanner. Our work indicates the magnetic field strength of current clinical MRI may be a limiting factor to detecting some white matter lesions in the preterm infant. Now that we can detect this injury, we also hope our findings may encourage MRI researchers to find more sensitive means to detect this injury with lower field MRIs that are widely available," said Back, an associate professor of pediatrics and neurology in the Papé Family Pediatric Research Institute at OHSU Doernbecher Children's Hospital.

High-field MRI scanners are still mostly used as a research tool and not widely available outside of specialized MRI research centers like OHSU, Back added.

White matter injury occurs during brain development when nerve fibers are actively being wrapped in myelin, the insulation that allows nerve fibers to rapidly transmit signals in the brain. The cells required to make myelin can be easily destroyed when blood flow to the developing brain falls below normal or when maternal infection occurs during pregnancy. The loss of these cells disrupts brain maturation and results in failure to make the myelin required for normal brain function.

Preterm infants are particularly susceptible to these injuries, which can result in lifelong impairments, including inability to walk as well as intellectual challenges.

Read more: http://www.eurekalert.org/pub_releases/2011-11/ohs-fuo110711.php

Poor Sleep Quality in First, Third Trimesters Linked to Preterm Births

Poor sleep quality in both early and late pregnancy has been linked to an increased risk of delivering preterm.

A study published in the Nov. 1 issue of the journal Sleep shows a significant risk for preterm birth in women reporting sleep disruptions during their first and third trimesters. The connection remained even after medical risk factors and income levels were taken into account.

"This supports the growing evidence that poor sleep is an important risk factor for preterm birth," said Michele Okun, PhD, assistant professor of psychiatry and psychology at the University of Pittsburgh School of Medicine.

"It likely occurs in the presence of other risk factors, but sleep can be measured easily and quickly during prenatal visits. Simply by assessing a woman's sleep quality, we may be able to identify a risk early in the pregnancy, when there is time to intervene. The data suggest that beneficial outcomes may be possible through modifications in behavior," Okun said.

Sleep quality in the second trimester did not correlate with increased risk. Okun said sleep often improves modestly during this part of pregnancy, although it is unclear why. One explanation might be hormones or other biological pathways playing a role, but there is no data.

Similarly, Okun and her co-authors suggest a biological cause for the increase in preterm births with disrupted sleep. Poor sleep quality has been shown to initiate inflammation, possibly activating the processes associated with childbirth prematurely. Sleep disruption also might do this in combination with stress, a known activator of inflammation.

Read more: http://www.sciencedaily.com/releases/2011/11/111101095304