Question about infertility...

Out of the 6 women I personally know who are ready for a baby and are actively trying, none of them can get pregnant. It’s been years of them not being able to have a baby. No one can give them a reason why.

I’ve noticed so many women have a hard time getting pregnant nowadays. I asked my mom and 3 aunts (who grew up in the 70s and 80s) if as many women had fertility issues when they were in their childbearing years. They said of the many of women they knew from high school, college, different jobs throughout the years, their communities..etc - you’d hear of MAYBE one or two women who were not able to bear children.

So my question is - why do people seem to have more fertility issues than ever nowadays? Does anyone have any theories?