[quote=njtosd]
From an evolutionary biology standpoint, a drop in fertility has never been “good for long term species survival.” Survival and reproduction is good for survival. Any genetic trait that causes a reduction in fertility will eventually disappear from the gene pool, leaving behind the more fertile survivors.[/quote]

Fertility rate in terms of “demographics” means a choice. Not in a women’s ability to have children. So you are talking about biological ability verse human choice. Big Difference! Yes I agree that would be BAD. Although, I have read about the reduction in male sperm count that has been going on for about 50 years, to which, they do not quite understand. At least, when I read about it in the 90s. But as far as I know, that has had only a negligible effect.

Developed countries usually have a much lower fertility rate due to greater wealth, education, and urbanization. Wikipedia has a pretty good entry on the “demographic transition” that is taking place. So, no, it’s no a biological deficiency, but a behavioral leveling off..