Can certain STIs make you infertile?

Yes, chlamydia and gonorrhea, if untreated, can cause pelvic inflammatory disease, a.k.a., PID. PID can cause scarring in the tubes that connect the ovaries and uterus and make it more difficult for an egg to pass through. Luckily, chlamydia and gonorrhea ae easy to test for and treat with antibiotics. You can prevent them in the first place by using a condom or internal condom when you have sex.