South Swindon MP Julia Drown is to leave Parliament at the next election.
Drown spearheaded a campaign on breastfeeding
The 41-year-old became a Labour MP in 1997 and says she wants to see as much as possible of her young children.
Ms Drown said she might well try to become an MP again some time in the future. But another poll win would mean her spending too much time in the job.
One of her most high profile moves during her time in Parliament was fighting to allow women MPs breastfeed in the Commons.
Ambitions for women
Ms Drown, who won a 7,341 majority at the last election, said in a statement: "I may well seek election as an MP again in
the future. But by the time of the next election I will have done the job for
"If I stood again that would mean I had spent 12 or 13 years in Parliament -
which is a long time, especially when I have young children whom I want to see
as much of as possible."
She added: "It is
important we have more women and more younger MPs in Parliament.
"I hope that
Labour will select another woman to fight the election in South Swindon and
continue to do our bit to make Parliament more representative of the country."