There is no lack of media coverage about women delaying motherhood, , so perhaps it wasn’t surprising to see a new study shows men are also waiting longer to become parents. The catch is just that there seem to be different factors at play.

For women, fewer teenage pregnancies resulted in a natural uptick in ages for first-time moms: According to a recent report in the Journal Pediatrics, the rate of teen pregnancies is down 61 percent since 1991. And the number continues to fall, with births to moms aged 15 to 19 down 9 percent from 2013 to 2014.

Meanwhile, according to the study out of Stanford University School of Medicine, today’s new dad is older than dads four decades ago by an average three and a half years: Between 1972 and 2015, the average paternal age went from 27.4 years to 30.9 years. Researchers also found the more years of education a dad has, the older he is when he greets fatherhood. Today, the typical college-educated new dad is 33.3 years old. The American data echoes stats from the United Kingdom, where the average age of dads is up from 30.6 years in 1991 to 33.2 in 2015.

In the United States, moms are still younger than dads. But the age difference is shrinking—down from 2.7 years in 1972 to 2.3 years in 2015—according to Michael Eisenberg, the study’s senior author.

“We’ve seen a lot of changes in the last several decades. Contraception is more reliable and widespread. Women have become more integrated into the workforce,” Eisenberg says in a media release. “This seems to be reflected in an increasing parity in parental ages over the last four decades.”

According to CNN, experts say it is harder to speculating about the underlying causes for the older ages of dads. Factors such as increasing levels of education, housing costs and economic conditions very different than those seen in the 1970s, which experts believe may be at play here. As Eisenberg notes, today, older dads are more likely to have better jobs than younger counterparts, and are more likely to live with their kids and be involved in parenting.

Older fatherhood has social implications as well. A study published in the Journal of the American Academy of Child and Adolescent Psychiatry found sons of older dads tend to be more intelligent, focused and less worried about fitting in than sons of younger dads.

“Our study suggests that there may be some benefits associated with having an older father,” study author Dr. Magdalena Janecka said in a media release. “We have known for a while about the negative consequences of advanced paternal age, but now we have shown that these children may also go on to have better educational and career prospects.”

Being biologically ready to be a parent is one thing, and being emotionally and financially ready is another. As long as the social factors influencing dads to delay fatherhood remain, there’s going to be a some grey hair in the maternity ward—and that’s OK. The best time to make a family is the time your family thinks is right.