Birth control is generally bad for societies, period. The moments you tell people they can fuck with no consequences, they do. Whilst 99.9% of the time it goes perfectly well, if you have a society of just 2000 people fucking once a week, you have at least one unplanned pregnancy a week. (I know, technically this decreases after the first pregnancy but the point still stands.)
After this, then dad runs away because he just wanted to bust and mum is left with the kid with society writ large paying for it. Society has to pay for it economically, via taxes. They have to pay for it politically, as unmarried mothers create voting blocks. And they have to pay for it socially as fatherless men are overwhelmingly involved in crime, especially crime against women.
One of my most controversial opinions is that birth control should be illegal, and I didn't come to that conclusion lightly. I used to think it was a 'privacy of their own room' kind of deal, but technology and its consequences is something that all of society gets a say in. Especially when it comes to children, that society ultimately exists to protect and nurture.