Kvitova just won her field-leading fifth tour-level title of the season in Birmingham, while an unseeded Williams beat world No. 17 Barty in three sets at the French Open.
"It's the right thing to do for these mothers that are coming back", said president Katrina Adams.
At the moment, Williams is entitled to a protected ranking after missing more than a year's tennis because of the birth of her daughter Alexis Olympia.
Caroline Wozniacki with the trophy after winning the Australian Open final against Simona Halep.
1 when she took her pregnancy break, and returned with a world ranking of 453.
England thrash Panama to move into last 16
Currently, England have two yellow cards to Belgium's three, meaning they currently top Group G by the slenderest of margins. Unsurprisingly, this would not produce a victor if Belgium and England draw.
Senegal will make Africa proud!
England and Panama have a 3:00 pm kick-off (1200 GMT) in Nizhny Novgorod meaning players could struggle in temperatures topping 30°C.
Supreme Court rules in favor of online sales tax
The court corrected a fundamental unfairness in sales tax collections, and state legislators have an obligation to follow up. Hart Posen an associate professor at the Wisconsin School of Business thinks that the decision can be a boon for Amazon.
In the wake of Williams's return to tennis this year, the WTA received criticism for not making seeding allowances specifically for pregnancy. The move ahead of the French Open sparked outrage.
Williams reached the fourth round before pulling out with a pectoral muscle injury, but she shouldn't face quite the same uphill battle at Wimbledon in a fortnight.
The U.S. Open, the second biggest tournament of the tennis year, will no longer penalize players whose rankings have tumbled because of maternity leave, starting with this year's tournament in August.
Majors give out seeding predominantly based on a player's ranking, which takes into account recent win-loss records. While she said she feels strongly that there should be no protection for players who have missed time because of suspensions (as Sharapova did following a positive test for a banned substance), Shriver sees the issue of pregnancy, which is often regarded the same as an injury in workplace policy, as different.
Each of the sport's four majors - Wimbledon and the Australian, French and USA opens - has the prerogative to seed players as it sees fit to ensure a balanced tournament.
'I am disappointed to inform you that I was forced to pull out of the Wimbledon championship which will start next week, ' he posted on Twitter.