On 28 February 1854, Cixi was elevated to the fifth rank of consorts and granted the title "Concubine Yi". In 1855, Cixi became pregnant, and on 27 April 1856, she gave birth to Zaichun, the Xianfeng Emperor's first and only surviving son. On the same day, she was elevated to the fourth rank of consorts as "Consort Yi". In 1857, when her son reached his first birthday, Cixi was elevated to the third rank of consorts as "Noble Consort Yi". This rank placed her second only to the Empress Niohuru among the women within the Xianfeng Emperor's harem.