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.
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.
the baby's head will actually grow thicker and stronger than on Earth. This is because your heart does not have to work so hard to move blood and other fluid from your feet to your upper body because there is no gravity.This causes the upper body to have more fluid and more pressure, which causes stress.
Your heart won't have to work as hard because there is no gravity to make blood circulation difficult. This takes a while to happen though. With a baby just born, probably the heart will never develop nearly as strong as a baby on Earth will.
Muscles and bones work together. if the child does a lot of exercise, the muscles get strong, making the bone very strong.
So, a baby born in space is going to have pretty strange and weak bones in most parts of their body. This shouldn't affect them too much if they spend their whole life in space, but they will be in a lot of trouble if they come back to Earth such as the heart muscle will not be strong enough to pump blood, leg muscles will be too weak for you to stand. However the baby can exercise muscles and bones to make them similar to the ones on Earth -but you still have heart and other things