Fatherhood is different from motherhood in important and unexpected ways, but in the past, most data about family life and parenting was about women. This left holes in our understanding of fatherhood and how fatherhood influences men’s lives.

While the National Survey of Family Growth and other sources have recent data on fathers, our lack of past data makes it hard to assess trends—and people want to know where fatherhood is going not just where it stands today.

A new report from the National Center for Health Statistics (NCHS) shows that it is still hard to get good data on fatherhood trends. The report used the 2002, 2006-2010, and 2011-2013 waves of the National Survey of Family Growth to estimate trends in the percent unmarried among new dads.

They found that the share of first-time fathers who were single decreased from 42 percent in the 1980s to 36 percent in the 2000s. Comparing trends for new moms (using birth certificate data for comparable time periods), we find that the share of unmarried new moms shifted in the opposite direction, increasing from 28 to 44 percent over roughly the same time period. So the trends for dads are interesting if true!

But we must be careful about using recent data to study past trends. The NCHS study had to use surveys from the 2000s to figure out the marital status of new fathers in the 1980s; in other words, the men surveyed were being asked about births two decades back. Unfortunately, the men surveyed in the 2000s were age 44 or younger, so the first births reported from the 1980s were almost exclusively from men reporting births in their teens and early 20s. The further back in time the study goes, the more the sample of dads is skewed young, and this skew shows up as an inflated percentage of single dads.

So what are the real trends since the 1980s? We don’t know the overall story, but the figure below shows our comparisons for a few age groups.

1. The percentage of young, new fathers who are unmarried has increased over time.
2. We have no trend data for older, new fathers, but most new fathers age 30 and older are married.

These new data on dads also show some other patterns that are very preliminary but worth further investigation. For example, few new dads in their 30s are single (20 to 25 percent), but other data show even fewer new moms are single at those ages (not shown). This pattern might indicate that when mixed-age couples become parents, their probability of being married depends not only on their average age, but also on whether dad or mom is the older member of the couple.

Our formal appreciation of fatherhood goes back to 1910 when the first Father’s Day was celebrated. Official statistics about fatherhood are still catching up, but we are starting to fill some important gaps. We must be careful to account for incomplete data in the past or we risk misidentifying trends, but data on fathers will definitely be providing new and important insights about parenthood.