Middle-class working mothers are leaving work as they are unwilling to behave like men, say researchers.
The research paper co-written by Emma Cahusac, series producer of BBC Television's The Culture Show and an organisational psychologist specialising in problems faced by organisations, and Shireen Kanji, Senior Lecturer in Work and Organisation at the University of Leicester School of Management, found that mothers in professional and managerial jobs are expected to stay late or get in early even if they have negotiated reduced working hours, and to socialise with colleagues or clients in the evenings - even though this clashes with their childcare responsibilities.
The researchers found that woman must do so as working culture is still organised by men, who are less involved in childcare.
Many of the interviewed women found it hard to combine work and motherhood because of the dominant culture of presenteeism - the notion that they should be at their desks until late, even if there was nothing to do.
The researchers found that before they had children themselves, women not only accepted but encouraged the masculine culture of the workplace.
The mothers interviewed also needed to hide the fact that they were parents - imitating a masculine trait.
The researchers interviewed 26 mothers based in London who had quit their jobs while pregnant, or following their return to work, but before their first child reached school age. The interviewees had been in professional and managerial jobs.
Twenty-one of them quit their jobs voluntarily - often because they had been sidelined after returning to the office. Susan moved within her bank to lower-status project work after she had her first child, for example.
The study has been published in the journal Gender, Work and Organization.