Yvette Cooper, one of Labour's rising stars, is to become the first government minister in Britain to take maternity leave.

In a move hailed last night by maternity rights campaigners, Ms Cooper, the public health minister, announced that she will take 18 weeks leave on full pay when she gives birth to her second child, which is due in August.

Ms Cooper, 31, who is married to Ed Balls, Gordon Brown's closest adviser, plans to stop working in July. She will return to work by the end of the year. After discussions with the health secretary Alan Milburn, she will take her maternity leave in line with Department of Health guidelines. Civil servants in the department are entitled to 18 weeks leave on full pay. Ms Cooper will therefore continue to draw her salary of £76,657 while she is on leave.

This is more generous than women's statutory rights. By law women are entitled to 40 weeks' maternity leave, 18 of which is paid - six weeks at 90% at full pay and 12 weeks at £60.20p a week. Mr Balls, 33, who is the treasury's chief economic adviser, will take paternity leave, as he did when their first child was born.

Ms Cooper, MP for Pontefract and Castleford, said yesterday that she was planning to have her baby at the NHS hospital in her constituency where she had her first child, Meriel, who is 20 months old. "We are planning to have the baby in Pontefract," Ms Cooper said. "The NHS staff there were wonderful to us last time round."

Maternity rights campaigners last night congratulated Ms Cooper for setting a good example to employees and employers alike.

Joanna Wade, a spokeswoman for the Maternity Alliance, said: "It is good to know that she feels confident enough to be up front that she will be taking time off. We strongly hope that this will set an example to high level employees that there are times when family has to come before work and mothers should not be punished for that."

Ms Cooper's announcement came as ministers finalise details of a government review of parental rights. They are expected to approve an increase in statutory maternity pay and in the amount of time mothers are allowed to take off work.

Campaigners are hoping that Tony Blair, who took two week's paternity leave after the birth of Leo last year, will endorse radical changes. Ms Wade said: "We are very hopeful, but there is a danger that the changes may not be as wholehearted as we would have liked to see."

Ms Cooper is regarded as one of the brightest stars in the government who is favoured by both the Blair and Brown camps. A former journalist, she was appointed to the frontline post of public health minister in 1999, two years after her election to parliament.