They report a dramatic decline in fertility, with effects on family life and civic culture.

There is a growing body of evidence that links environmental factors to decreases in fertility.

Current data suggests a possible role of osteocalcin in male fertility.

All these factors should contribute to a decline in fertility.

Women whose age is becoming a major factor in fertility may not want to spend that extra time.

This reduction in fertility is noted to a much greater extent after age 40.

That could account for some of the increase in fertility.

It seems obvious to blame the fall in fertility from the mid-1960s on the pill and legal abortion.

Let us look first at the easier one - explaining variations in fertility.

The model correctly predicts a downturn in fertility around 1964.