It has been documented that calcium is mobilized from a mother's bones during pregnancy and helps build the baby's bones, a natural process. The loss of bone mineral density during pregnancy may be 5%, but that bone density is typically replaced within a year. Breast feeding appears to assist bone remineralization in the mother.

There is some evidence to indicate that the number of pregnancies or the first pregnancy at a higher age are risk factors for later life bone loss. However, many variables are involved and no clear cause-effect relationship has been documented.

At any rate, it is clear that bones "take a hit" ...