Democratic presidential bet Hillary Clinton has received the endorsement of abortion service provider Planned Parenthood, which called her the "nation's best presidential candidate for reproductive rights, hands down."

"There's no question: Hillary Clinton holds the strongest record on reproductive rights of all presidential contenders in not just this election, but in American history," a statement on the Planned Parenthood website says. 

"She doesn't just support women's health — she has been a pro-active leader on expanding access to women's health care. In fact, no other 2016 candidate has shown such strong, lifelong commitment to the issues Planned Parenthood Action Fund cares about," it says.

The women's health organisation believes that its services such as birth control and abortion are under "unprecedented attack," adding that this is why it is important that America vote for someone who will take a stand with them at all costs.

"Clinton has demonstrated over and over that she wants birth control to be affordable for all women. That's why she called the Supreme Court's Hobby Lobby ruling 'deeply disturbing' for allowing some bosses to deny their employees affordable birth control coverage. It's no wonder she had a 100 percent rating on the Planned Parenthood Action Fund scorecard while she was in the Senate," it says.

Throughout her political career, Clinton introduced eight pieces of legislation with the purpose of expanding and protecting access to reproductive health care. At the same time, she is the sole candidate for the 2016 elections who testified before a Congressional committee how essential abortion is in reproductive health care, the Planned Parenthood statement says.

Planned Parenthood says it values Clinton because she is the only presidential candidate who has defended the organisation in debates.

"It's nearly impossible to count the many times she has stood up for Planned Parenthood throughout her life, but even in small areas she has stood up for Planned Parenthood big-time," it says.