# See, your relative

"Pay attention, because what I am about to say is both true and important: your relative"

# your relative Elizabeth

If you need to state a specific relationship, Elizabeth was probably Mary's aunt or great-aunt.

# has also conceived a son in her old age

"Elizabeth has also become pregnant with a son, even though she is already very old" or "Elizabeth, even though she is old, has also become pregnant and will bear a son." Make sure it does not sound as though both Mary and Elizabeth were old when they conceived.

# the sixth month for her

"the sixth month of her pregnancy"