Women's Six Nations Player of the Championship Poppy Cleall says England "can't carry on playing professionals v amateurs" in the tournament.
The Red Roses were the only fully professional side in the 2021 edition and won a third successive title.
In an Instagram post Cleall called on unions to "invest in the girls".
"Invest in the passionate, dedicated athletes you see week in, week out - they represent your nations so well," the 28-year-old forward wrote.
The 2021 Women's Six Nations was played later than the men's tournament and in a reduced format because of disruption caused by the coronavirus pandemic.
England have dominated the championship since becoming professional in 2019, winning a Grand Slam later that year and in 2020.
France - the side England beat in the tournament's first final in April - are semi-professional, while a limited number of Scottish players are on paid contracts. Ireland, Wales and Italy's teams are all amateur.
Cleall added: "When they asked me for a quote about winning the Player of the Championship, I had to be subtle: 'I hope other female rugby players and athletes are given the same opportunity to be the best they can be'.
"What I really wanted to say was, 'we can't carry on playing professionals v amateurs'.
"They [the players] deserve better and they deserve the resources to reach their potential sooner rather than later. It has to be a level playing field."