Generally, it is claimed that gestation theory was originated locally in Tibet, with only a single origin. This author proves that there are two sources, both derived from India. One is a combination of gestation theory from rGyud-bzhi, i.e. Astangahrdayasamhita, and the Great Ratnakuta, and the other, from Somaradza, also derived from the Great Ratnakuta. The dates of writing of modern edition of Somaradza and rGyud-bzhi are still uncertain yet. Based on the linguistic features, this author claims that Somaradza was written before the Tibetan version of Great Ratnakuta (9 century), while rGyud-bzhi, after the translation of Astangahrdayasamhita (10-11 century).