Tbh when you decide to stick it in you're making a choice to deal with the consequences. So is she mind you (provided it's consensual) but to say you can just "waive" off child support is ridiculous.
You should either be able to waive off both or neither. Letting you waive off one but not the other supports the rights of one gender over another. Since there is no consent required from men regarding abortion even though they are both responsible, men should be able to waive all responsibility for the potential kid. Having that system in place would require that both people come to an understanding about the situation and one can't coerce the other in any way. It would make things riskier for women but they would factor that in when deciding who to sleep with. Men already have to factor in that they may be signing on for 18 years of child support if they're sleeping with someone they don't trust without protection, so that's still consistent.