Despite the length of the marriage that Empress Wang had with Emperor Gaozong, she did not bear him a son, and by the time that she became empress, he had already had four sons with his concubines—and the mother of the fourth son Li Sujie, Consort Xiao, who had also given birth to two daughters (the later Princesses Yiyang and Gao'an), was particularly favored. Liu Shi suggested to Empress Wang that she suggest that Emperor Gaozong's oldest son Li Zhong, whose mother Consort Liu was of low birth, be made crown prince, so that she could be endeared to him. Empress Wang was able to persuade Emperor Gaozong's powerful uncle Zhangsun Wuji to support the plan, and in 652, Li Zhong was created crown prince.