“Just the two of us is awesome,” said Sara Tenenbein, a 31-year-old blogger and consultant living with her husband in Los Angeles. “Maybe we don’t need to add more humans to the equation.”

Not having children is still rare among married women like Tenenbein, but less so than it used to be, according to an analysis by the National Center for Family & Marriage Research at Bowling Green State University, which examined figures from the National Survey of Family Growth.

The percentage of married women ages 40 to 44 who had no biological children and no other kids in the household, such as adopted children or stepkids, reached 6% in the period from 2006 to 2010. That’s a small but statistically significant jump since 1988, when only 4.5% of married women had no kids.

The increased numbers echo a wider trend over recent decades, as more American women have reached their 40s without bearing children.