A study published today in scientific journal PLoS ONE* examines the fundamental correlation between age and fertility in women. This ground-breaking research is the first of its kind to collate the decline of the “ovarian reserve” from pre-natal to menopausal females. It demonstrates that as women reach 30, the potential number of eggs available for fertilisation is just 12% of their maximum ovarian reserve. By 40, only 3% remains.

This important discovery illustrates the rapid decline in fertility as women age, debunking the myth that because they continue to produce eggs, their fertility will remain constant. The number of eggs women are born with can vary considerably, ranging from over 2 million to less than 35,000. Of those, only around 450 will fully mature. The greater the number and quality of eggs that are available, the more the likelihood of one maturing into a pregnancy.

The evidence presents a convincing case for contemplating parenthood at an earlier stage. As the average age of women undergoing IVF increases, the financial and emotional implications of delaying conception are often considered all too late.

Now more than ever, women are putting off fundamental decisions about parenthood, in order to get a firm foot on the career ladder. By burying their heads in the sand, they are not only facing the possibility of problematic fertility in later life but also conforming to an imposed notion that career and family life are incompatible.

Each year 30,000 women lose their jobs simply because they are pregnant. Rather than tacitly competing in an unfair, masculine marketplace, women should be campaigning for flexibility and equality, which recognises and celebrates the uniquely female ability to reproduce. This week, Allen & Overy, a magic circle law firm, went some way to bridging this gap through the introduction of part-time hours for partners in an effort to encourage more women into these roles.

Although the professions are steadily improving in this regard, attitudes will not completely change until women begin to lead from the front, face the truth of their own biology and demand that their reproductive choices be accommodated.

*PLoS ONE is an international, peer-reviewed, open-access, online scientific publication.

Wallace WHB, Kelsey TW (2010) Human Ovarian Reserve from Conception to the Menopause. PLoS ONE 5(1): e8772. doi:10.1371/journal.pone.0008772

http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0008772