Great information!

I hadn't thought about that and am glad because getting 1 million people to Mars will be very hard in a period of catastrophically low fertility for Earth civilisation.

The big issue is ensuring high fertility for those Mars colonists when almost all advanced civilisations on Earth, the only ones that can provide sufficiently educated and skilled colonists, have very low fertility.

A pro-natal culture will need to be carefully nurtured and women will need to find Mars attractive.