New plans to offer junior doctors better access to flexible working will remove a major disincentive to work in the NHS, according to the British Medical Association (BMA).
Under the terms of an agreement between the BMA and NHS Employers, it will be easier for junior doctors to share a whole-time equivalent 'slot'.
A clearer range of reasons for applying for flexible training will also be considered, including religious commitments and professional development.
The BMA estimates the plans will double the number of doctors choosing to work flexible hours over the next three to five years.
It said that at present, only one in 20 junior doctors trains flexibly, but half would like to.
Simon Eccles, chairman of the BMA's junior doctors committee, said poor work-life balance could be a nightmare for junior doctors.
"Many - especially those with families - would be forced to leave the NHS if they did not have access to flexible training," he said. "I am delighted that the NHS has made this commitment to retaining staff and improving junior doctors' working lives."
Gill Bellord, head of pay and negotiations at NHS Employers, said the new contract will encourage NHS trusts to offer flexible training opportunities to more junior doctors who cannot work full-time.
"We also expect NHS trusts to offer more family friendly training opportunities for full-time junior doctors, including help with childcare and the option of working hours to fit in with family life," she said.