Excerpts from Books and Wikipedia
"Unfortunately, when Thutmose II died unexpectedly, the young son was not yet old enough to rule on his own. Hatshepsut, therefore, stepped in to rule temporarily as regent on his behalf. But when it came time to hand the throne over to him, she refused to do so. She ruled for more than twenty years, while Thutmose III waited—probably impatiently—in the background." [1177 BC, Kindle, Location 653] "When Tuthmosis II died before the age of thirty-five, his only son—now Tuthmosis III—was still a child. At once Hatshepsut claimed her right, as the baby’s aunt and stepmother, to rule as his regent. For three or four years at the beginning of the regency, she appears in carvings standing behind the young Tuthmosis III in a properly supporting role. But sometime around 1500, Hatshepsut began to build a huge temple: a mortuary temple, a place of worship which had once stood at the foot of a walkway from a pyramid, and now often served as the primary burial monument itself. . . . Twenty-one years after her husband’s death, with her co-ruler and stepson now well into his twenties and hardened by years of fighting in exile, Hatshepsut died." [Bauer: Ancient World, p. 208-9]