John Sweeney investigates the secretive world of the family courts and asks whether some parents may have unfairly lost their children forever. The crucial evidence against them came from doctors, who said that tiny fractures on their babies' x-rays were evidence of abuse. But some experts now believe that lack of vitamin D or rickets might point to another cause for the fractures. One young mother has taken desperate measures after losing her daughter - she has gone on the run from the UK to have her second child abroad. But even this drastic step may not keep her out of the reach of social services