asalaam alaikum
A quick, short and sweet response:
For generations after generations through out human history people have been marrying at the age of 9 and 10. By 16 they were old enough to lead an entire battalion! For thousands and thousands of years human beings did not regard early marriages to be hazardous. If early pregnancies were hazardous, surely the human civilisation across the planet and through out the history should have noticed a pattern. Something like that cannot be missed out or ignored for thousands upon thousands of years so easily.
On the other hand contemporary medicine is known to have changed its stance on various issues several times. In the 70s the mothers in England were being told NOT to breastfeed. And now, women who do not breastfeed are looked down on.
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