A severe decline in childbirths has occurred over the past half-century, which will lead to considerable population declines, particularly in industrialized regions. A crucial question is whether this decline can be explained by economic and behavioral factors alone, as suggested by demographic reports, or to what degree biological factors are also involved. Here, we discuss data suggesting that human reproductive health is deteriorating in industrialized regions.
Widespread infertility and the need for assisted reproduction due to poor semen quality and/or oocyte failure are now major health issues. Other indicators of declining reproductive health include a worldwide increasing incidence of testicular cancer among young men and alterations in twinning frequency. There is also evidence of a parallel decline in rates of legal abortions, revealing a deterioration in total conception rates.
Subtle alterations in fertility rates were already visible around 1900, and most industrialized regions now have rates below levels required to sustain their populations. We hypothesize that these reproductive health problems are partially linked to increasing human exposures to chemicals originating directly or indirectly from fossil fuels.
In my opinion, economic and behavioral factors CAN explain much of the phenomenon. Notwithstanding, this theory is interesting.
Is air pollution linked to birth rate? I know of no research linking them. The most polluted air was in England but no pop decline. The signs of decline started in France in the 18th Century. Greece and Rome in the antiquity suffered from the same problem and they were not burning fossil fuels. It is a mystery.
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