You and others KEEP saying this.
If you're getting married, chances are good you're going to be having sex with that person.
Unless one of you -- by chance or by desire -- has ended up infertile or purposefully sterilized, you will run the risk at some point of conceiving.
First, No birth control is perfect.
Second ... regardless our ability to gloss over the Essential function of sex that is procreation
-- even as we pin the fault for our infidelities on our Evolving Animal Nature(s), pretending for a moment the point of animal sex is not reproduction but consensual thrill of profound intimacy, in and out of Heat or Season --
the fact is that sex is not just a lot of fun and a constant distraction, it's actually a means of bringing forth a whole new human being.
So, save for the failsafe arrangement that is infertility, sterility or homosexual sex, children ARE necessarily a consideration and there's really no point in marrying anyone with whom you wouldn't have kids or with whom you couldn't grow old and ("Let's face it fellow bees," say old Bob Dole) dysfunctional.
Unless, of course, you're pro-choice and you can just kill the kid or you're pro-Transformer and intent to use surgery and chemicals to pickle yourself so you can look Lifestyle-ish 'til you drop.
for all the talk of our being apes in pants -- human beings are unique on the planet for being able to choose to obligate themselves.