That cumulative stress can do a massive number on most people that inside their heads atleast, fantasies of not having children (regardless of how) become normal and simply unspoken.

In non American cultures your more likely to find households where one set of the granparents literally live with the family and in doing so are the to help relieve the load of raising children fulltime. Having that help that you know you can trust and without being super rich hiring a nanny would massively alleviate that hidden extreme of stress that most modern parents deal with. Those fantasies of life without kids(again, regardless of how) suddenly become more moot.

This movie highlights that aspect of having kids. Something else, you cant discipline children today like our grandparents were disciplined because of how fast people would scream child abuse for anything. This is dangerous because kids arent stupid, love testing the limits of what they can get away with, and know they can practically commit murder without their parents being allowed to discipline them. This leads to all of the problems we have with overly disrespectful children and an even higher level of stress on the parents.

After a while, killing your kids suddenly doesnt seem as extreme with a bit of outside influence like biological warfare as mentioned in the movie. Overall i thought this movie was suprisingly good for what it was