Tens of thousands of incidents have led to a mother or baby being harmed in NHS hospitals in recent years, it has been reported.
More than 276,000 incidents are said to have been logged by staff between April 2015 and March 2017 through a voluntary scheme run by the regulator NHS Improvement.
According to the BBC most were minor or near misses, although nearly one in four incidents led to the mother or baby being harmed.
In a reported 288 cases there was a death.
Potential lapses in care included short delays in obtaining medication or failing to complete records properly.
More serious incidents included babies being deprived of oxygen and life-threatening conditions not being diagnosed, the BBC reported.
Health Secretary Jeremy Hunt said every serious incident will be investigated by a new watchdog.
He said: "Mistakes in maternity care can lead to heartbreaking tragedies for mothers and babies.
"Whilst it's encouraging that hospitals are being increasingly honest when things go wrong, my top priority as Health Secretary is to reduce avoidable harm in hospitals and save families from the agony that comes with it."
The new regulator will investigate serious incidents "without fear or favour, and send warnings across the NHS to prevent repeat mistakes. These important changes will save babies' lives, and avert pain and heartache for thousands of families", Mr Hunt said.