According to a study by a Finnish research team, infants born prematurely are more likely to have visual and hearing problems than full-term babies.
The report, which was published in US medical journal Pediatrics in July, shows that the incidence of sensory impairment decreased the closer to the due date a baby was born.
The most important factors associated with increased risks of hearing loss and visual impairment were bleeding within the skull and convulsions, the study said.
According to the report, the risk of sight and hearing problems was the highest among very preterm infants born before 32 weeks of pregnancy, but the risk increased for all preterm babies – defined as those born between 32 and 36 weeks of pregnancy.
For example, the incidence of hearing loss among babies born at 34-36 weeks was 25 percent higher than among full-term babies, while very preterm babies were twice as likely to have such impairment.
The study's results on blindness and visual disturbances were similar.
The study included all infants who had been born alive in Finland between 1991 and 2008. However, babies who died before the age of one year or who had any major birth defects were excluded, as were babies with insufficient data. In total, more than one million infants were analysed.
About six percent of children in Finland are born prematurely.