The age at which someone becomes fertile is difficult to know for sure.
We tend to think that females are fertile once they begin to menstruate. However, ovulation (the release of a fertile egg) might not occur with a female’s first few menstrual cycles.
For males, fertility requires the ejaculation of sperm in semen. Sperm production does not begin until after puberty has started, but exactly when is difficult to know for sure. There are a number of studies that have used different ways of estimating when sperm production begins.
Some studies look for sperm in urine samples because it is known that sperm can get into the bladder of adult men after ejaculation. Studies like these show that the average age at which sperm can first be collected from urine samples is 13 years , ranging from 11-15 years.
Other studies have estimated the age at which boys become fertile based on their age at first ejaculation. These studies show that the average age is also around 13 years, ranging from 10-18 years (and has decreased over the last 100 years; at least in Bulgaria).
The production of sperm and ejaculation of semen are both required for fertility. Sperm production might begin before ejaculation but it is also possible that ejaculation could occur before enough sperm are being produced to be make it into the ejaculate.
It seems like if you’re able to ejaculate, then it’s safest to assume that you are capable of making babies.
Tim Moss
Healthy Male Health Content Manager
Associate Professor Tim Moss has PhD in physiology and more than 20 years’ experience as a biomedical research scientist. Tim stepped away from his successful academic career at the end of 2019, to apply his skills in turning complicated scientific and medical knowledge into information that all people can use to improve their health and wellbeing. Tim has written for crikey.com and Scientific American’s Observations blog, which is far more interesting than his authorship of over 150 academic publications. He has studied science communication at the Alan Alda Centre for Communicating Science in New York, and at the Department of Biological Engineering Communication Lab at MIT in Boston.
