The Nose Knows… at least it used to.
Perhaps you've heard this before... According to the book Taking Sex Differences Seriously (a very well researched book, albeit from an evolutionary perspective), "Research indicates that the birth control pill may interfere with a deep, unconscious mechanism involving the sense of smell by which women have ensured that the partners they choose can help them produce healthy offspring... women... regularly prefer the smell of men whose immune system is unlike theirs in terms of key proteins that detect and attack invaders... Moreover, a woman's sense of smell is most keen around the time that she ovulates and is most fertile.
The birth control pill changes all this. Women on the Pill do not have a heightened sense of smell at any part of their cycle. And as science writer Deborah Blum explains... when on the Pill, women have smell preferences that are "reversed... almost completely." Women taking oral contraceptives prefer the smell of men with immune systems similar to theirs.
Scientists are beginning to wonder if the birth control pill has led to a whole generation of marriages that have had more difficulty producing offspring, or that have produced more vulnerable offspring..." (109-110)