The Male Biological Clock

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There is extensive literature that clearly defines the impact of increased maternal (mother’s) age on a couple’s likelihood of conceiving and reproductive outcomes. However, there has been fairly limited research done on advanced age of the father and how this may affect the offspring.  As it is increasingly common for couples to try and conceive later in life, advanced paternal age is something we want to look at – does the male biological clock exist?  And if so, what’s the impact on a male’s reproductive potential?


In Fertility and Sterility this month, a group of researchers looked at the existing research on the male biological clock and its implications.


Some of the pertinent findings from this review include the association of “advanced paternal age” (the actual age is yet to be defined, more on this later) with:


1. Decline in sperm motility and morphology


2. Decline in rate of pregnancy; increased incidence of pregnancy loss


3. Negative impacts on embryo development and reproductive outcome in sperm donor cycles using male donors >35


4. Increased risk of neurocognitive defects, some forms of cancers, and genetic syndromes related to aneuploidies (incorrect number of chromosomes)


5. Very minimal change in the likelihood of conception - ie. older sperm are almost as likely as younger sperm to fertilize an egg, but the complications associated with that embryo/pregnancy are greater


6. Increased DNA fragmentation, which negatively affects the outcomes of IUI and IVF procedures


There are several hormonal changes that occur in men as they age.  Testosterone and SHBG (sex hormone binding globulin) are affected, with a gradual decrease in bioavailable testosterone as men get older.  In the initial literature, it was suggested that men over the age of 60 see testosterone levels decrease, but we are now starting to see more evidence that decline in T for men in their 20s and 30s is much more common.  This lower testosterone can not only lead to low libido and lack of muscle mass gain, but can also affect sperm quality and reproductive potential.


So how do we define “advanced paternal age?”  When does the biological clock start ticking for men?


For women, reproductive potential starts to decrease at the age of 35 because multiple risks start increasing exponentially at this time.  But for men, the medical community has yet to set a threshold - studies define advanced paternal age as anywhere from >30 to >55.  Part of the difficulty of reaching a consensus is that some risks increase when the father is >35, others don’t increase until he’s over 55 (like schizophrenia risk).  Other changes, like decreased sperm parameters for example, decrease slowly and continuously with time; there is no definable point where the quality heads south suddenly, so it becomes difficult to define the age at which the decrease is significant. 


Despite being able to put a finger on the exact age at which paternal fertility potential declines, the literature definitely shows that it decreases over time.  So - there may never be a category of “advanced paternal age” that’s recognizable, but when men are in their 40s and 50s and want to father children, it is clearly important to think about sperm quality and overall health.


With naturopathic and Chinese medicine we are able to reduce the rate at which the biological clock is ticking.  For men especially, assessing for antioxidant capacity, mineral status, and acid/base balance is a good place to start.  Sperm are incredibly sensitive to their environment!  And as men age, increases in oxidative stress and decreases in mineral absorption and availability start to affect the quality of sperm they produce.  This is where we intervene.  We alter the cellular environment, provide the required nutrients, and let the body do what it’s supposed to.


The great news is that men are always producing new sperm – a brand new batch takes about three months to develop.  So lifestyle changes and supplementation for three months before trying to conceive is important for all men, especially as they get older.


If you’d like to know more about the functional medicine in-office testing that I do to determine the quality of the cellular environment, and how this can increase the quality of sperm you produce, feel free to ask me at clinic or book in for a free 15 minute consult.   It definitely takes two to tango, and we need to assess our future dads, especially over the age of 35, to make sure their contribution is healthy!


In health,

Dr. Kali MacIsaac HBSc, ND
Naturopathic Doctor


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