older dads

What about the guy?  As fertility doctors we focus a lot of our energy on investigating the woman and counselling couples about the success rate, risks and outcomes as they relate to the woman.  Partly this is because testing of the male is more straightforward and partly because the success rate is usually more dependant on female factors, but outcomes are different: the male matters more than we previously thought.

The health of a child conceived through IVF or other fertility treatments has been thought to be related almost exclusively to the woman's age, BMI, lifestyle, supplements she takes and her overall health.  That's still mostly true, except we now understand the role of male's age on the health of the child.  The male's age matters.

Men's contribution to the child is genetic.  They do not provide mitochondria or other cell structures.  The genetic contribution is coded on the male's DNA.  The DNA degrades over time, slowly and in a few different ways.  This manifests in children having a higher risk of disease the older their father is at the time of conception.  

 

A recent review of the topic was published in Fertility and Sterility (Reference: Nybo Andersen AM, Urhoj SK. Is advanced paternal age a health risk for the offspring? Fertil Steril. 2017 Feb;107(2):312-318).  Children conceived when the father's age at the time of conception was > 40 were at higher risk for the following:

  • miscarriage and stillbirth (controversial)
  • achondroplasia (a type of dwarfism)
  • neurofibromatosis
  • Marfan's syndrome
  • cleft palate
  • acute lymphatic leukemia
  • autism spectrum disorders
  • schizophrenia

 

Now, this is where we need to pause and put these risks into perspective.  These risks, while increased, are still low.  For example, the average risk of achondroplasia is 1/15,000 births.  If that risk if tripled because the male age is 50 that becomes 3/15,000 births (< 0.01%); still a rare event.  Autism effects about 1-2% of children (depending on what source you review).  If the father's age is over 40 the risk increases by about 40-50%.  So, still most children conceived by older men will not have autism.   This is not to say we should ignore these risks.  We should know them, understand what they mean for the individual couple and let them decide how it effects their plans to conceive.  It should be noted that these risks increase with age - so a 70 year old man has a higher risk than a 45 year old man for these conditions in their children.

 

These studies are admittedly controversial so I am on quoting the large, reproducible ones that have tried to control for the effect of advanced maternal age.  After all older men often are reproducing with older women so it's important they factor the risk the woman brings to the child in their observations.

 

The more you know.....

Dr. Beth Taylor MD, FRCSC
Reproductive Endocrinology & Infertility