That’s a great question! A lot of the time when a baby is born without a limb it is a birth defect. This means that when the baby is forming in the womb and the limbs are starting the form something does not happen as it should. This can be down to a number of reason. These can be genetic abnormalities, growth restrictions or mechanical forces.
I wish I knew! Like Fiana said it could be so many different things. For example, research has shown that if the mother is exposed to certain chemicals or viruses while pregnant, or takes certain kinds of medications, the chance of a baby born without limbs is higher. Then, it can also be due to an unfortunate accident during fetus development in the womb.