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When Does Fertility Stop?

Miami Study

A recent study by researchers at the University of Miami has found that women, when they are at their most fertile points during any given month, tend to stay away from male relatives so as to avoid any evolutionary hint of inbreeding. The behavior has long been observed among other animal species, and when the cell phone records of four dozen participating women were analyzed retroactively, they revealed the same pattern of behavior. Women were 50% less likely to call their dads during high fertility days.

Optimum Fertility Ages

Meanwhile, the constant coverage in the media of older women having babies is creating a distorted view of the normal female fertility cycle. At age 25, women have already lost 80% of the eggs they were born with. By 35, that figure has reached 35%. Several hundred Canadian women were surveyed about their knowledge of their own fertility, with data confirming that they were under a generally false impression of their potency in later years. Few seemed to realize that by 30 years, the monthly likely success rate of pregnancy was 22% and would drop to 18% by age 35 and 5% by age 40.

Another factor that women tend to overlook when reading about a celebrity like actress Kelly Preston having a baby at age 48 is that she is likely doing so with someone else's eggs. Overall, the tipping point in terms of fertility for women is 35, while for men it is the age of 40. First-born children of older mothers also were found to face more health risks.