Men, delayed childbearing and age-related fertility decline

While media reports regularly remind us of women's biological clocks and warn of the dangers of women leaving it 'too late' to have children, until recently little attention has been paid to the role of men in timing when to have children, and the effect of age on male fertility. However, July 2017 saw a surge of interest in this in mainstream media, following evidence from the Beth Israel Deaconess Medical Center and Harvard Medical School presented at the European Society for Human Reproduction and Embryology's (ESHRE) annual conference. Findings from a study of 18,802 IVF cycles suggest that amongst couples undergoing the procedure, for men over 35 increasing age was associated with lower cumulative incidence of live birth. Outlets including The Guardian, the BBC (including BBC Radio 4) and BioNews picked up on these findings, bringing this discussion into the public domain. The Guardian and the BBC also reported findings from a systematic review, from the Hebrew University of Jerusalem, of recent trends in sperm counts, which reported a decline in sperm concentration and count between 1971 and 2011.

Thus the accepted wisdom that men can continue to have children into later life, easily and without consequence, has been called into question. In some articles, authors blame men's lack of awareness of age-related fertility decline, and lazy or glib attitudes towards having children, either explicitly or implicitly. Alongside this, coverage of recent research (Inhorn, Baldwin, Gurten) on egg freezing suggests that women freeze their eggs because they are not able to find a suitable male partner; there is a 'dearth of eligible men' wherein the number of qualified, professional women is not matched by an equivalent number of qualified, professional men. These accounts have added weight to the idea that men's roles in relationships, in starting a family, and in when to start a family are of crucial importance.

Prior to this, to a large extent media attention had mirrored social science research on the topic: the minimal focus on men being greatly outweighed by a focus on women. This is also reflected in our national data collection: while the Office for National Statistics (ONS) gathers data on women's ages at the birth of their first child, this is not the case for men; for men, a distinction between first and subsequent children is not made, as it is for women. Consequently, while we can track changes in the age at which women are becoming mothers, we cannot track trends in when men are becoming fathers.

Nonetheless, ONS data does suggest that the average age of men at the birth of any children has risen from 31.1 in 1993 to 33.2 in 2015. Research suggests that the majority of men want children, and being an 'older' father isn't something most desire. Men identify certain pre-conditions as necessary before embarking on parenthood, including being in a good relationship with the right partner and someone whom they feel would make a good parent; having financial and material security; and feeling emotionally and psychologically ready. Men's aspirations to be both the breadwinner, as well as a nurturing and involved father, also create added pressures.

However, scientific evidence about the impact of age on men's fertility, while still contested, appears to be a growing. A 2015 systematic review of 90 studies identified age-associated declines in semen volume, percentage motility, progressive motility, normal morphology and unfragmented cells. Elsewhere, evidence suggests that advanced paternal age is also linked with increased risk of infertility, miscarriage and various pathological conditions in offspring. In addition, the 2013 NICE fertility guidelines reported that there was now evidence of declining male fertility with increasing age, for the first time.

All these developments point towards the need to take greater consideration of the role of men in reproductive timings (and in whether, when and why women opt to freeze their eggs) and related research – both social and medical. If age does indeed play a role in men's fertility health, this needs to be taken into account in research, policy and practice.

Finally, we need to question why women's behaviours and reproductive 'choices' are routinely held to account in delayed childbearing, not men's; a greater focus on men will go some way to redress the balance. In 2013 Reproductive Biomedicine Online published a special issue on age-related fertility decline, beginning with the piece 'Cassandra's prophecy: why we need to tell the women of the future about age-related fertility decline and 'delayed' childbearing'. In the lively debate that followed, authors considered whether 'telling' women is sufficient, and grappled with how this complex issue can be addressed. Perhaps the recent media interest in men, age and fertility is a sign that the time for a full and frank debate about talking to men about age-related fertility decline – both women's and men's - will soon be upon us.