If a baby were born in space (microgravity) and grew up there, would it influence the structure of the bone or body? Would microgravity cause the muscles to be smaller than a child growing up normally on Earth?
If a pregnant woman flies in space and gives birth almost right away, the baby will be born pretty normal because it will develop in the womb very normally at Earth's gravity. What happens then is very interesting.
The bone cells are programmed to grow--they don't stop until you are a teenager or so. But it is gravity as a stress that makes the cells in the bones have the right alignment, or stack up properly and pull the bone so that it forms straight. Without gravity, the baby's bones won't get long and thin like adult bone. They will be very easy to break, and they won't grow as fast. This is true for arms and legs.