Average paternal age rises in the USA

By Dr. Ananya Mandal, MDAug 30 2017

According to a latest study by the researchers at the Stanford University School of Medicine, the average age of fathers of the new born babies in United States has risen by 3.5 years over the last four decades. The study was published yesterda in the journal Human Reproduction.

Average paternal age rises in the USA. Image Credit: Lopolo / Shutterstock

It seems that men in their 40s make up for being fathers of around 9 percent of all U.S. births. Men over the age of 50 form around 1 percent of all fathers of newborns.

This study from the Stanford researchers is the first comprehensive look at all the live births that have been reported to a federal data depository in the United States between 1972 and 2015. This accounts for 168,867,480 births. The data came from the National Vital Statistics System that is an intergovernmental data-sharing program funded by federal Centers for Disease Control and Prevention.

The study is authored by Yash Khandwala, a medical student at the University of California-San Diego who was a research scholar to Michael Eisenberg, an assistant professor of urology at Stanford.

The team looked at the National Vital Statistics System that records births and deaths reported by all 50 states along with self reported maternal and paternal ages along with levels of  education and race and ethnicity of the parents.

The authors say that the CDC routinely comes up with data and information about mothers in relation to births all over the country.

There is little information regarding fathers of these babies. Eisenberg said that one in every nine live birth had little or no information about the father. That could be because the father was unknown or because the mother did not wish to reveal details about him.

Black and Native American mothers showed least amount of paternal data reporting whereas older and more educated women tended to provide more details about the father.

Results of this study showed that between 1972 and 2015, the average paternal age rose from 27.4 years to 30.9 years. When seen according to ethnicities, Asian-American dads, especially Japanese- and Vietnamese-American dads were an average of 36 years and over. These are the oldest in the analysis. As education levels rose, so did the paternal ages. A father with college degree typically was around 33.3 years old. Black fathers were found to be the youngest in the study.

Results revealed that fathers of newborns who were older than 40 years rose from 4.1 percent to 8.9 percent and those over 50 rose from 0.5 percent to 0.9 percent during the assessment period from 1972 to 2015.

United States is not alone in this assessment. Most industrialized countries show a similar trend. According to Eisenberg this rise in paternal age has a significant public health impact. For starters as a man gets older before his first child is born, he is less likely to father too many children. Further all men acquire an average of two new genetic mutations in their sperm each year.

Older fatherhood is linked to several conditions including higher rates of chromosomal abnormalities, childhood cancers, autism, schizophrenia and rare genetic disorders.

On the other hand older fathers also indicate a better settled and financially stable father who can give their children a better upbringing. Also older fathers are more likely to live with the children and give them a more involved parenting explained Eisenberg.

The mother’s ages are also on the rise he said. With advancing age the average age difference between mothers and fathers have shrunk from 2.7 years in 1972 to 2.3 years in 2015. This is seen in all races and ethnicities in the study he noted.