Earlier quoted context omitted.
If your relationship balance and trust is based on whether or not your partner can secretly make babies with you without your consent, that is something to be addressed (in a human way, not by using ultrasound on your testicles).
Relationships are hard and often imperfect. People often lie and act irrationally. I've seen justifications like "he won't leave me if I have a baby with him". As men, this is absolutely something that we should worry about.
> People often lie and act irrationally.
If that is your fundamental truth in interacting with your partner(s), your relationships will never really get anywhere. It is just not good advice to tell people to do so, unless you want them to never create meaningful connections with their partners.