In the Margaret Atwood novel the series is based on, most people are infertile thanks to exposure to pesticides, toxic chemicals, and STIs. Although there's no proven link between the pesticides used today and fertility issues, the STI concern is definitely real: If left untreated, both chlamydia and gonorrhea can lead to pelvic inflammatory disease. As the CDC explains , that condition can cause damage to your reproductive organs and, therefore, infertility. Unfortunately, rates of chlamydia and gonorrhea are at an all-time high right now in the U.S. Of course, that doesn't mean that mass infertility necessarily follows that trend, but it is a good reminder to keep your sex safe, to regularly check in with your gyno about your risk for STIs, and to definitely not delay treatment if you do think something might be off.