Your parallels have one major failure point. A UBI enables the lowest income earners in society to become contributing members of said society which in turn helps the whole society. An unplanned child cannot be a contributing member of society for nearly 2 decades. Worse still for a mother who may already be struggling and now has to struggle even harder.
Are you including the paternal figure here too?
Men are made responsible by law wether they like it or not. The law goes after him and rapes his finances for 18 years and if he misses one payment he is thrown in jail. But unlike men, women can opt out of responsibility. She can abort, put up for adoption, abandon her baby in a public toilet,building or even chuck it in the garbage to be found and no offence has been committed and she faces no financial penalties. That's female privilege for you.