Everyone knows that advanced maternal age (over 35) is linked to decreases in fertility and a slew of other pregnancy complications. How about paternal age or the age of the dad? After all, it takes two to make a baby. Does the age of the sperm matter? We know of many celebrity dads fathering children well into their 50s and 60s. Donald trump became a father for the fifth time at the age of 59. Does paternal age matter?
Advanced Paternal Age
Paternal age is the age of the man contributing the sperm. Typically, this is the father of the child. However, there is no agreement on what age defines “advanced paternal age”. Unlike maternal age, which dramatically affects fertility at age 30, 35 and then again at 40, paternal age is associated with a slow gradual decline in fertility. Paternal age isn’t nearly as widely studied. The best definition out there for advanced paternal age is greater than 40. However this is an estimate and varies dramatically from person to person.
Impact of Paternal Age on Fertility
The research is difficult to assess because most of the time, when the father is older, the mother is also older. However, the research out there does show that paternal age causes a decline in fertility. This is most likely due to a decrease in the quality and quantity of sperm. I have summarized my findings below:
- One study in the UK found that men over 45 took five times longer achieve pregnancy than men less than 25 (Fertility & Sterility). 1
- In a French study, looking at intrauterine insemination (IUI), men less than 35 had double the success rate of men greater than 35.2
- Another study in the UK found that men over 40 were 30% more likely to experience fertility when controlling for maternal age.3
- A meta-analysis of male sperm found that increased paternal age was associated with decreased sperm count, decreased sperm motility, abnormal morphology, decreased semen volume and decreased sperm concentration. The biggest difference was found in sperm motility, which is essential for transporting the sperm from the site of ejaculation, through the cervix and uterus and into the fallopian tube to meet the egg.4
It is also worth mentioning that as men age the prevalence of erectile dysfunction increases. This makes it more difficult for men to have sex and may result in a lower frequency of intercourse. If this is the case, a change in the frequency of sex can certainly decrease the chances of becoming pregnant.
Impact of Paternal Age on Genetic Disorders
We know that advanced maternal age significantly increases the risk of genetic disorders, specifically down syndrome. Paternal age appears to have a similar effect, but to a lesser degree. The thinking is that men produced sperm throughout their lifetime. Therefore as a man ages his sperm have undergone thousands of replications. Each replication carries a risk of a mutation, which could cause an anomaly. It is estimated that 5% of trisomy 21 (Down Syndrome) is caused by paternal factors (NJEM).5 If there is a family history of genetic disorders or if you are concerned about your child having a genetic disorder, it is important to meet with a genetic counselor. A genetic counselor can explain the options of genetic testing to decrease the risk of genetic disorders.
Impact of Paternal Age on the Risk of Autism
Some studies have additionally shown relationships between certain outcomes and paternal age. Among these are decreased cognitive ability, schizophrenia and autism spectrum disorder. As you can imagine these outcomes can be scary for couples involving an older man. Much of the research that exists on autism makes it very difficult to identify risk factors associated with autism. Now that we know there is a relationship between the age of the father and the risk of autism, the burden of having children early is going to be shared between the man and woman. In the future we may be seeing more men freezing their sperm just like women have been freezing their eggs. This is a summary of my findings on the relationship between paternal age and autism spectrum disorder:
- One review found that when paternal age increased by 10 years, the risk of autism increased by 21%. 6
- Another study found that children born to men over age 40 were at a 3.3 times increased risk of developing autism as compared to those born to men under age 20.7
- A study in Israel found that children born to men over age 40 were 5.75 times more likely to develop autism than children born to men under age 30.8
At the end of the day the age of the man does affect his fertility especially as he gets into his 40s. You also start to increase your risks of genetic anomalies, cognitive disabilities and autism. So when either the man or woman is older, putting off ttc can have serious consequences.
To find out if you are ready to have a baby, checkout my article Are You Ready to Have a Baby?
- Hassan, M. A., & Killick, S. R. (2003). Effect of male age on fertility: evidence for the decline in male fertility with increasing age. Fertility and sterility, 79, 1520-1527.
- Mathieu, C., Ecochard, R., Bied, V., Lornage, J., & Czyba, J. C. (1995). Andrology: Cumulative conception rate following intrauterine artificial insemination with husband’s spermatozoa: influence of husband’s age. Human Reproduction, 10(5), 1090-1097.
- Ford, W. C. L., North, K., Taylor, H., Farrow, A., Hull, M. G. R., & Golding, J. (2000). Increasing paternal age is associated with delayed conception in a large population of fertile couples: evidence for declining fecundity in older men. Human Reproduction, 15(8), 1703-1708.
- Johnson, S. L., Dunleavy, J., Gemmell, N. J., & Nakagawa, S. (2015). Consistent age-dependent declines in human semen quality: a systematic review and meta-analysis. Ageing research reviews, 19, 22-33.
- Antonarakis, S. E., & Down Syndrome Collaborative Group*. (1991). Parental origin of the extra chromosome in trisomy 21 as indicated by analysis of DNA polymorphisms. New England Journal of Medicine, 324(13), 872-876.
- Wu, S., Wu, F., Ding, Y., Hou, J., Bi, J., & Zhang, Z. (2017). Advanced parental age and autism risk in children: a systematic review and meta‐analysis. Acta Psychiatrica Scandinavica, 135(1), 29-41.
- Buizer-Voskamp, J. E., Laan, W., Staal, W. G., Hennekam, E. A., Aukes, M. F., Termorshuizen, F., … & Ophoff, R. A. (2011). Paternal age and psychiatric disorders: findings from a Dutch population registry. Schizophrenia research, 129(2), 128-132.
- Reichenberg, A., Gross, R., Weiser, M., Bresnahan, M., Silverman, J., Harlap, S., … & Knobler, H. Y. (2006). Advancing paternal age and autism. Archives of general psychiatry, 63(9), 1026-1032.