"I support them because I am a woman," Mrs Odinga said. The ban started on April 30 and scheduled to end May 6.
Mrs Odinga said the conjugal boycott had already worked by drawing attention to the squabbling which has hit Kenya’s power-sharing government, the BBC reported.
"There are many women who are suffering rape, there are many women who are suffering hunger. And yet the leadership is not thinking about the common person. They are thinking about who should be the leader of what and what," the prime minister’s wife told the BBC’s Network Africa programme.
She, however, refused to be drawn on whether the fiery wife of President Mwai Kibaki would join the movement. Questioned whether she would ask Mrs Kibaki to join her in the strike, she replied: "Please let me not answer that question, you can ask her."
Lucy Kibaki has a notoriously fiery temper. In February, she publicly criticized the security minister, a close ally of her husband.
And in 2005, she sparked a media furore when she stormed into the offices of a leading media company to protest at its portrayal of the first family and slapped a cameraman.
The ban was imposed by groups which fear the row could lead to new unrest.
Some 1,500 people were killed and 300,000 forced from their homes when violence broke out after disputed elections in December 2007. The clashes came to an end when Mr Odinga agreed to join the government as prime minister in February 2008 but his relations with President Kibaki have soured in recent weeks.
The Women’s Development Organization coalition imposed the sex boycott on Wednesday and urged Mrs Odinga and Mrs Kibaki to join them.
Patricia Nyaundi, executive director of the Federation of Women Lawyers (Fida), one of the organizations in the campaign, said they hoped the seven-day sex ban would force the squabbling rivals to make up.
"Great decisions are made during pillow talk, so we are asking the two ladies at that intimate moment to ask their husbands: ‘Darling can you do something for Kenya?’"