Are American women really having fewer children than ever before?

A new government study suggests that fertility rates in the US have reached an all-time low, but Pew Research Center says the issue is pretty complicated.

The findings from the National Center for Health Statistics show that in 2013, there were 62.5 births for every 1,000 women of childbearing age in the US. But Gretchen Livingston, a Pew researcher, clarified those numbers.

“Is this really a record low? The short answer is: It’s complicated. That’s because there are different ways to measure fertility. Three of the most commonly used indicators of fertility are the general fertility rate (GFR); completed fertility; and the total fertility rate (TFR). All three reflect fertility behavior in slightly different ways – respectively, in terms of the annual rate at which women are presently having kids; the number of kids they ultimately have; or the hypothetical number they would likely have based upon present fertility patterns.”

So, if you’re looking at the general fertility rate, or how many births happen each year from women of childbearing ages 15 to 44, then yes, 2013 was a record low.

But if you’re measuring completed fertility rate — the number of children a woman has in her lifetime — the lowest was in 2006, when the fertility rate fell to just 1.86 births per woman.

A third indicator — total fertility rate — estimates lifetime fertility and fell to a record-low rate of 1.74 births in 1976. These nuances show that fertility, however it is defined, isn’t as cut and dry as it might appear.