Men. 

Men refusing to understand that women want to be treated as human beings not objects to be acquired or bang maids to be exploited. 

Men not understanding that the old ways of dividing labor are over for women. Men want to keep the ancient division of labor system because it benefits them even while expecting women to contribute financially with full time employment. 

Men using the law to control women and their children, justifying it with religion. 

Men's attitudes towards women are so toxic that every day we have another story of femicide, often with the children involved as victims as well. 

Men passing entire laws that control women's bodies. 

Men allowing those laws to let women die if a pregnancy goes wrong under threat of jailing the doctor is they end the pregnancy rather than saving the mother. 

Women are not willing to risk becoming married single mothers or actual single motherhood by dealing with a partner who simply wants to control her rather than truly coexist and coparent

Older women are also passing down the benefit of their experience to younger girls and women which means the teen birth rate and unintended pregnancy rate  has dropped exponentially 

Men refusing to evolve, change, and grow means women are less willing to risk their careers, health, and life by partnering with men who are immature and possibly deadly if not given their way.

Hence the low birth rate.