I agree that both men and women can be equally feckless in their choice-making.
However, nature/society is already far more heavily weighted toward making a woman face up to the consequences of her actions (regarding conception) than it is a man.
Scenario 1) 2 feckless people = conception results
Woman: Chooses an abortion (if this option is actually available to her), pays any money toward having it done, 100% alone deals with the physical effects of gestation until termination, and 100% deals with any physical/mental fallout afterward (not a risk-free procedure).
Social stigma and condemnation from certain groups of people afterward.
Man: Doesn't need to do anything. Effectively zero consequences.
Scenario 2) 2 feckless people = conception results
Woman: Has the baby. 100% alone deals with all the physical effects of full gestation and childbirth (up to and including death). Spends the next 18 years of her life nurturing that child into an adult human being along with all the physical, emotional, and majority of financial costs that involves.
Man: No physical effects. May or may not have to pay a small percent of his earnings for the next 18 years (depending on his circumstances/honesty). May or may not have any involvement in the child's life at his own whim.
These are just two scenarios, but even in cases where the man does suffer more than he usually would (ie. he really wanted the child), his mental suffering is still completely outweighed by the mental suffering, physical suffering, and physical risk (up to death) of forcing a woman to birth against her will.
Additionally, if you really wanted women to have 100% choice, 100% responsibility for the child after the birth, then they would be allowed to fully dictate any involvement the father could have (even if he wanted to be a fully involved father with shared caring arrangements, she could 100% deny this at her whim).
I don't think many men would want that or find it fair either.