The BBC has received around 200 complaints after a documentary about pornography was shown at 9.15am.
Sally Magnusson presented the four-part series Streets of Vice
Britain's Streets of Vice, presented by Sally Magnusson, featured interviews with several people who make a living from the UK's porn industry.
Media regulator Ofcom said it was looking into the matter after receiving 34 complaints.
"I firmly believe it is in the public interest to address these issues," said BBC daytime controller Alison Sharman.
"This is the first time there has been such a powerful and challenging documentary series shown on daytime television," she said.
"Challenging the perceptions of daytime television has been one of my most important focuses since taking on the role of controller of BBC Daytime in January 2002. The films have been carefully edited and transmitted to ensure they are appropriate to be transmitted during the day."
The programme included workers in the sex industry describing their jobs, and discussed porn films, explicit websites and sex shops in London's Soho.
John Beyre, director of TV monitoring group Mediwatch, said they had also received a number of complaints.
"People are very angry that they and their children were confronted with pornography on BBC One at 9.15 in the morning," he said.
"I don't know what the BBC were thinking of to schedule this series at this sort of time."
A spokeswoman for the BBC said, "This sensitive subject was approached in a suitable way for an adult audience. "
"The drugs and sex industries are a legitimate area of public concern and are topics which have frequently been covered in daytime talk shows."
"We have worked closely with the relevant agencies and in conjunction with experts in the field, as well as with the full co-operation of BBC Compliance and Editorial Policy departments."
The spokeswoman added that the programme had been deliberately scheduled during term time and the nature of the content had been clearly stated beforehand.
However, many of those who protested were concerned that a larger number of children were off school than usual due to the snow, meaning they would be more likely to have seen it.
The four-part series also featured programmes on prostitution and heroin addiction.