“there are effective contraceptives to prevent pregnancies”
There’s an average failure rate of about 5% annually.
That’s mainly because lots of women don’t always take their pills on schedule. If they took them on schedule it would be under 1%.
Young men should be aware of that real world 5% failure rate.
The oral contraceptive (both the combined contraceptive pill and the protestogen-only pill) have a typical use effectiveness rate of around 91%. .Around 9 in 100 women using the combined pill will get pregnant in a year.
So say you've got 10,000 undergraduate women at your university, and say further than all are sexually active and all are on the Pill. Expect 900+ surprise pregnancies per year from this group.
The various jellies, jams, foams, sprays and barriers are much less effective. and yield a much higher pregnancy rate. Except for the condom, not one of them protects against STI's, and some even enhance risk for viral, retroviral or bacterial STI's.
The LARCs (Long-Acting Reversible Contraceptives) --- injection, implant, patch, ring, IUD --- while about 99% effective for preventing pregnancy, are ALL associated with elevated STI rates as well as stroke, thrombosis, depression and (ironically) decreased libido..
Enjoy.
Conception occurring is a success rate.