New York, Feb 16 (IANS): Children who have undergone heart surgery as infants may risk hearing loss by the age of four, in addition to poor language skills and cognitive problems, researchers have found.

Researchers discovered that around 21 per cent of 348 pre-schoolers, who had survived cardiac surgery, suffered hearing loss. This rate was 20 times higher than that prevalent among the general population.

For the study, published in the Journal of Pediatrics, the researchers analysed neurodevelopmental outcomes in these children. A total of 75 children were found to have developed hearing loss.

Other factors common among the hearing loss cases were gestational age younger than 37 weeks, a confirmed genetic anomaly and longer postoperative length of stay.

The researchers found children with hearing loss had lower scores on measures of language skills, cognition (IQ testing), and executive function and attention.

The study suggested that children who undergo heart surgery should have their hearing evaluated by age 24 to 30 months, to increase their chances of receiving timely medical intervention.

"Children born with life-threatening heart defects require a great deal of sophisticated care before and after surgery," said lead author of the study Nancy B. Burnham, a nurse-practitioner in the Division of Cardiothoracic Surgery at the Children's Hospital of Philadelphia.