Findings from a new observational study presented by the Center for Reproductive and Genetic Health (CRGH), London stated that the female partners of men older than 51 years of age have less success in IVF treatments, due to a natural decline in male fertility and sperm viability. The conclusion, presented at the European Society of Human Reproduction and Embryology comes from an analysis of around 5,000 in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) cycles carried out between 2009 and 2018.
Historically, women have borne societal scorn for not bearing children early, due to female fertility having an established end at menopause. The impending loss of fertility at menopause is also crudely known as a ‘ticking biological clock.’ Male fertility is often treated as a constant, which enforces the popular stereotype of the ‘unattractive’ older woman and the attractive older man.
But very few men over 51 years old, in the study, met the standards for average semen quality set by the World Health Organization. Clinical pregnancy rates for the female partners of these men also declined with increasing paternal ages: 49.9% for partners of men under 35, 42.5% for partners of men aged 36-40, and 30.5% for partners of men over 51. When these results were re-analyzed in a statistical model that took into account the fertility effects of maternal age, the probability of pregnancy still decreased when the father’s age was over 51.
In his presentation of the study at the European Society of Human Reproduction and Embryology, Dr. Guy Morris, who helped carry out the analysis, said, “There may well be a public perception that male fertility is independent of age. Stories of celebrity men fathering children into their 60s may give a skewed perspective on the potential risks of delaying fatherhood. Indeed, in natural conception and pregnancy, it is only recently that evidence of risks associated with later fatherhood has become available. These more recent studies contrast with decades of evidence of the impact that maternal age has on fertility outcomes.”
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The study also helps undermine the tired biological clock trope that’s thrown at women who aren’t planning to have children in their twenties. Ever since the term was invented in the 1970s, women have been pressured to date early and birth children early so their biological clock wouldn’t betray them. “We are raised to believe female bodies are time bombs,” writes Moira Weigel for The Guardian. While evidence of male fertility decline means the onus of fertility at an older age is shared by both men and women, this doesn’t mean either men or women should be subject to the additional pressure of an imaginary ticking clock.