The measure is on top of a promise of 3,000 more midwives, funded under the extra £2.5bn a year raised for the NHS by measures including a "mansion tax".
It comes as David Cameron is to confirm a Conservative government would match a Lib Dem pledge to spend an extra £8bn on the health service by 2020.
A Tory spokesman said the coalition had recruited more than 2,100 midwives.
Labour says it will enshrine the one-to-one pledge in the NHS constitution, as part of measures funded through a tax on properties valued at more than £2m, a crackdown on tax avoidance and a levy on tobacco firms.
This issue includes NHS funding, GP access and social care, particularly of older people.
Policy guide: Where the parties stand
Speaking at the launch of Labour's health manifesto in West Yorkshire, party leader Ed Miliband said he was proposing: "One midwife, fully committed to you, that's what we mean by one-to-one care - from when you go into labour, to when your baby is safely delivered, keeping you secure throughout the most important journey you will ever take."
Speaking on BBC Radio 4's Today programme, shadow health minister Liz Kendall said the pledge would lead to safer births, fewer caesareans, less post-natal depression and a better start in life for babies.
Around £480m a year is spent on clinical negligence cover for maternity services, she added, saying many midwives were quitting the job because of "huge pressure", leading to worse care.
In 2013, the National Audit Office said an extra 2,300 midwives were needed in order to meet a "widely recognised benchmark" of one midwife to 29.5 births.
The Royal College of Midwives welcomed Labour's announcement but said community services also needed sufficient staffing for care before and after birth.
A Conservative spokesman said management cuts and increased efficiency had allowed the coalition to recruit more than 2,100 midwives.
"Since 2012, we have been investing and training 2,500 midwives every year to ensure that future mothers have a named midwife overseeing their care," he said.
Liberal Democrat spokesman Lord Scriven said: "Labour has a shameful track-record on midwifery. When in government they oversaw a critical shortage of staff with midwives' workload increasing by a quarter in just six years."
Labour is pledging one-to-one midwife care for women during childbirth in its health manifesto for England.