Giraffe gestation usually lasts around 400 to 460 days, after which a single calf or on rare occasions twins are born. The mother giraffe give birth to her young standing up. The calf emerges head and front legs first, having broken through the fetal membranes, and falls to the ground, severing the umbilical cord. So in a nutshell, the mother gives birth standing up but the calf is not born standing up.
Generally, the mother giraffe can be found grooming the newborn soon after birth and helping it stand up. Newborn giraffes are about 6 feet tall and within a few hours after being born can usually run around. For the first few weeks of life, they will spend most of their time hiding.