The news that autism and schizophrenia may be related to paternal age has brought mixed feeling to the legions of women who have long been warned about the dangers of trying to have children too late. Finally, it seems that the imperative to reproduce sooner rather than later will fall on prospective fathers as well as mothers. But calling this new awareness of the health risks of paternal age a ‘biological clock’ is somewhat misleading as the issues men and women face have profoundly different implications (for more, read Jeffrey Kluger’s story in the new issue of TIME, available to subscribers here).
The term originally had nothing to do with fertility. In the medical literature, it referred to the mysterious mechanism behind recurrent biological changes—daily shifts in body temperature, for example—and applied to men, women and amoebas alike. But during the 1970s, as women began flooding the work force, it began to be used—often by men—as the temporal waning of a woman’s ability to conceive, the force that ends ovulation and brings on menopause. “The clock is ticking for the career woman,” warned Richard Cohen in the Washington Post in 1978.
Today the biological clock refers to the drop off in female fertility after the age of 35, a decline that can begin even earlier. According to the American Congress of Obstetricians and Gynecologists (ACOG), “age is a significant factor influencing women’s ability to conceive.” A classic study of artificial insemination showed that after 12 cycles, 74% of women younger than 31 became pregnant, compared to 54% of women more than 35 years old. Moreover, when older women do get pregnant, the chance of having a miscarriage rises dramatically.
Although a woman’s risk of bearing a child with a disorder like Trisomy 21 (Down’s Syndrome) also rises after the age of 35, the biological clock really refers to whether she can conceive at all. (The fact that the cut-off point varies from woman to woman only brings more uncertainty and anxiety.) For men, the calculus is different. Although waiting longer may slightly increase the risk of having a child with a disease caused by a genetic mutation in the sperm, the overwhelming majority of their children will be healthy. The question then, for the older man, is not whether he can have children, but whether he should.
But here’s the problem. We rarely, if ever, tell older woman that they shouldn’t try to conceive. Instead we offer them genetic testing and the opportunity to terminate in the face of genetic anomalies, if they wish. We downplay the additional health risks to the child. In that sense, suggesting that older fathers shouldn’t have children would present something of a double standard.
Perhaps instead we should be looking at our insistence on unnatural fertility. We are the only species that delays reproduction beyond the onset of sexual maturity. It is our unnatural desire to postpone childbearing by decades, while searching for the right partner or establishing a chosen career, that has led to the dilemmas facing older parents — both men and women. The solution to our dilemma may be at hand: while we can’t stop getting older, we can be sure our sperm and eggs never do by freezing them for future use. In that case, the slow ticking of the biological clock may soon be a thing of the past.