Even as advertisers are embracing new configurations of families — two dads, say, or grandparents raising grandchildren — there’s one group that feels left out.

Women who are childless. Or as they also call themselves, the child-free. Or even the NotMoms.

According to census figures, more women in the United States are childless than at any other time since the government began keeping track in 1976. Nearly half of women — 47.6 percent — between the ages of 15 and 44 did not have children in 2014, up from 46.5 percent in 2012. And 15.3 percent of women ages 40 to 44 are childless. The numbers are growing internationally as well.

Despite these statistics, “the majority of marketing talks to adult women like they are all moms or want to be mothers,” said Adrianna Bevilaqua, chief creative officer at M Booth, a public relations company.

Melanie Notkin has made a career of catering to women who don’t have children but love them — she is the founder of the website SavvyAuntie; coined the term “professional aunt, no kids,” or PANKs; and is the author of “Otherhood: Modern Women Finding a New Kind of Happiness.” She wonders why companies, always eager to target a potentially lucrative demographic, seem to be ignoring this one.