British Prime Minister David Cameron has called for an urgent reconsideration of the way the prison system in England and Wales treats pregnant women and mothers with babies, the media reported on Sunday.At present, when a woman gives birth while serving a custodial sentence, she is usually transferred to a prison's mother and baby unit (MBU) for an initial period, BBC reported.MBU policy requires that these units should be available to accommodate babies up until the age of 18 months."It's time to think seriously about whether this is the right approach," Cameron said.The review will look at whether female offenders with babies could be dealt with by special problem-solving courts, housed in resettlement units or electronically tagged, rather than being locked up.Justice ministry figures suggest 100 babies spent time living with their mothers in prisons last year.Cameron said it was "absolutely terrible" to think of infants spending time behind bars.