Biologic Clock Ticks for All

Successful reproduction is generally an age related phenomena. Ovarian function in terms of egg quantity and quality is medically referred to as ‘Ovarian Reserve’ and is a function of what is euphemistically called, a woman’s ‘Biologic Clock.’ The impact of maternal age is well studied especially as it negatively affects women’s reproductive potential over age 35 and especially in women 40 years of age and older. As women age there is less chance of becoming pregnant and a higher chance of adverse outcomes including low birth weight, preterm birth, pregnancy loss, and chromosomal abnormalities. Couples regardless of age who desire children should be aware that the risks of disorders in children increases continually over time because the biologic clock ticks for all.

Less well appreciated is that men, too, have a ‘Biologic Clock’ in terms of their reproductive potential with advancing paternal age negatively impacting fertilization, embryo development and reproductive outcome. This is especially apparent in men over age 45 and especially in men over 60 years of age. Testicular function declines in both the cells responsible for making testosterone and those making sperm. Low testosterone levels as everyone knows from watching commercial television and their myriad of pharmaceutical commercials, leads to decreased libido, frequency of intercourse, erectile dysfunction. Low testosterone can also compromise sperm production, sperm motility, sperm morphology, and sperm function. Sperm from older men are less likely to fertilize healthy eggs and if they do these fertilized eggs are less likely to cleave into good quality embryos, to implant and to lead to a healthy pregnancy due to the increased risk of chromosomal and other genetic mutations in the sperm of older men. There is an association between advanced paternal age and pregnancy loss even when correcting for maternal age. Birth defects are also more common in the offspring of men of advanced paternal age as are autism spectrum disorders, childhood malignancies, and premenopausal breast cancer in women born to fathers of advanced paternal age.