The study showed that the autism spectrum disorder rate in children was 1.5 per cent in the maternal Tdap vaccinated group and 1.8 per cent in the maternal unvaccinated group.
"Infants are at the highest risk of hospitalization and death among any population subgroup after contracting a pertussis infection, a highly contagious respiratory disease also known as the whooping cough," said lead author Tracy A. Becerra-Culqui, a post-doctoral research student at Kaiser Permanente -- a US-based health care company.
"Pregnant women can be reassured by this study that there is no indication of an increased risk of autism spectrum disorder in children after being exposed prenatally to the Tdap vaccine," Becerra-Culqui added.
The study, published in the journal Pediatrics, looked at the autism diagnosis for nearly 82,000 children.
The Advisory Committee on Immunisation Practices, which provides guidance on the use of vaccines for the US, recommends pregnant women receive the Tdap vaccine to prevent pertussis infection, but some women still hesitate.
"The link between vaccination and development of autism has been refuted by many rigorous scientific investigations. Unfortunately, the misconceptions still generate concerns," the researchers said.
For the study, published in the journal Environmental International, researchers hypothesized that in utero exposure to polybrominated diphenyl ethers (PBDEs)--a type of flame retardant that is known to have adverse effects on brain development--might alter the brain processes involved in reading.
"Since social processing problems are not a common aspect of reading disorders, our findings suggest that exposure to PDBEs doesn't affect the whole brain--just the regions associated with reading," said study researcher Amy Margolis from Columbia University Vagelos College of Physicians and Surgeons in the US.
An estimated two million children have learning disorders; of these, about 80 per cent have a reading disorder. Genetics account for many, but not all, instances of reading disorders.
According to the study, the research team analysed neuro-imaging data from 33 5-year-old children--all novice readers--who were first given a reading assessment to identify reading problems. They also used maternal blood samples, taken during pregnancy, to estimate prenatal exposure to PDBEs.
The researchers found that children with a better-functioning reading network had fewer reading problems. The also showed that children with greater exposure to PDBEs had a less efficient reading network.
However, greater exposure did not appear to affect the function of another brain network involved in social processing that has been associated with psychiatric disorders such as autism spectrum disorder.
Although exposure to PDBEs affected reading network function in the 5-year-olds, it did not have an impact on word recognition in this group.
The finding is consistent with a previous study, in which the effects of exposure to the compounds on reading were seen in older children but not in emergent readers, the researchers said.
"Our findings suggest that the effects of exposure are present in the brain before we can detect changes in behaviour," Margolis said.
"Future studies should examine whether behavioural interventions at early ages can reduce the impact of these exposures on later emerging reading problems," Margolis added.
(IANS)
The study, published in the journal Archives of Disease in Childhood, examined the mental health of NICU graduates in childhood (four to 11 years) and adolescence (12 to 17 years), using data from parent and youth psychiatric interviews.
The research builds on previous studies that suggest extremely low birth weight babies who are admitted to the NICU are more likely to develop mental health issues during those years.
"Advancements in the medical care of patients admitted to the NICU have led to improved outcomes for infants and families, and the need for NICUs has increased in Canada and the US," said study senior author Ryan Van Lieshout from McMaster University in Hamilton, Canada.
"However, little has been known about the mental health of the broader population of NICU graduates, particularly as they enter late childhood and adolescence," Lieshout added.
The study used a provincially representative cohort from the 2014 Ontario Child Health Study, led at McMaster.
Parents provided data on psychiatric disorders for 3,141 children aged four to 11 and in 2,379 adolescents aged 12 to 17. Additionally, 2,235 adolescents aged 12 to 17 completed the interview themselves.
According to the researchers, children aged four to 11 who had a NICU admission were nearly twice as likely to have any mental disorder or have more than one mental illness.
The risk of separation anxiety disorder, specific phobia, attention deficit hyperactivity disorder, or oppositional defiant disorder also increased, the study said.
At the age of 12 to 17 years, NICU graduates remained at nearly twice the risk for developing any psychiatric problem, multiple psychiatric problems and oppositional defiant disorder as reported by adolescents and their parents.
"Existing follow-up guidelines of preterm infants suggest monitoring for mental health issues, and this study provides preliminary evidence that in the future it may be prudent to expand this to all infants who stay in a NICU regardless of birth weight status," said Van Lieshout.
(IANS)