.. have another child... i.e. why did she get pregnant?
Survival of the species and tribe, as our ancestors have done for centuries after disasters, wars and plagues in order to get us to dominance of the planet... It's quiet literally in our DNA to behave this way...
It's kind of the point of the movie... The primacy familial and intergenerational bonds as survival instinct...
This is the anti-superhero movie... instead of loner-billionaire psychos as our protagonist heros aligned with a militeristic government to save the day (iron man, batman, Joker, Killmonger and other losers, etc...) we have a normal family in an existential scenario, similar to one faced by our anscestors for countless generations and they prevail due to their familial bonds... As our anscestors have in the past...
This is what a strong woman has actually looked like throughout human history, not a roided up skinny girl with 'abs' and invariably some type of daddy issues (Tomb Raider, etc...) ...
The pregnancy is key to the movie in suspense as well as to the higher level themes and subtext of the movie...