I wonder if the Canadian model of 1.5 years of maternity leave is a must for humanity's survival in the long term. IMHO (without much research) i see many women

I wonder if the Canadian model of 1.5 years of maternity leave is a must for humanity's survival in the long term. IMHO (without much research) i see many women who have no choice but to feed formula milk to their babies (at daycares) as they are not around to breastfeed. Now i read somewhere that without breastfeeding the baby enough the women's body generates lesser and lesser breastmilk. But, Doctors always recommend breastfeeding as it gives maximum immunity to the baby. In the absence of a proper/sufficient maternal leave (like the Canadian one), i wonder if the next generations of humans become less and less immune to diseases.