[PAR] [TLE] 1981 US Open – Women's Doubles [SEP] Billie Jean King and Martina Navratilova were the defending champions but only Navratilova competed that year with Pam Shriver. [PAR] [TLE] Billie Jean King [SEP] Billie Jean King ("née" Moffitt; born November 22, 1943) is an American former World No. 1 professional tennis player.  King won 39 Grand Slam titles: 12 in singles, 16 in women's doubles, and 11 in mixed doubles.  King won the singles title at the inaugural WTA Tour Championships.  King often represented the United States in the Federation Cup and the Wightman Cup.  She was a member of the victorious United States team in seven Federation Cups and nine Wightman Cups.  For three years, King was the United States' captain in the Federation Cup.
[PAR] [TLE] 1981 US Open – Women 's Doubles [ SEP ] Billie Jean King and Martina Navratilova were the defending champions but only Navratilova competed that year with Pam Shriver . [PAR] [TLE] Billie Jean King [ SEP ] Billie Jean King ( " née " Moffitt ; born November 22 , 1943 ) is an American former World No . 1 professional tennis player . King won 39 Grand Slam titles : 12 in singles , 16 in women 's doubles , and 11 in mixed doubles . King won the singles title at the inaugural WTA Tour Championships . King often represented the United States in the Federation Cup and the Wightman Cup . She was a member of the victorious United States team in seven Federation Cups and nine Wightman Cups . For three years , King was the United States ' captain in the Federation Cup .
How many Grand Slam titles were won by the defending champion of the 1981 US Open - Women's Doubles?
How many Grand Slam titles were won by the defending champion of the 1981 US Open - Women 's Doubles ?
39
39