GerTzedek, it all depends on many factors. You have to remember that quite aside from modern divorce or out of wedlock pregnancies, children growing up fatherless has been a fact of life forever. Every war that ever was has reduced the number of available fathers. Where I live, many fathers are away for months at a time working, or in the navy. The small percentage of women who choose to have a child without a father will hardly make a dent in the statistics.
More importantly, you don't seem to grasp that few children up isolated entirely from significant persons, male and female, other than their parents. Most will have grandparents, uncles, aunts, cousins, neighbours, family friends with more or less influence in their lives.
Because of the kind of work I was involved in, I have known many, many single parent families, a few same sex parent families, and lots of two parent families. In all cases, Mom, Dad, or Mom and Dad were supplemented by relatives and close friends in the care of children. Families don't have to be cloned stereotypes of Mom and Dad to raise healthy, happy kids.
There's very little evidence that children are better off emotionally with a Dad, but they often are financially better off with a Dad. That says more about the way we employ and pay women than about the importance of Dads.
Conversely, single dads are quite capable of raising children on their own, employing the very same support system of relatives and friends.
When my parents were children, it was fairly common, if a family felt another baby on the way was too much for the finances, to give the baby or another child to an aunt or uncle to raise. Our stereotype of the isolated two parent nuclear family is more informed by television than reality.