New York City's subway system is taking a cue from London by introducing “Baby on Board” buttons for pregnant riders to help them secure often elusive seats on public transit. The yellow and blue button is the latest effort by the subway authority to encourage New Yorkers to be more polite to fellow commuters. (It previously targeted the "manspreading" epidemic.)
"Please offer me a seat" buttons will also be available to older people and disabled riders.
“Pregnant riders, seniors and those with disabilities often need seats more than others, but their condition may not always be visible,” Ronnie Hakim, the authority’s interim executive director, said in a statement. “We hope this campaign will help their fellow riders to be more willing to offer them a seat without having to ask a personal question first.”
The campaign by New York's Metropolitan Transportation Authority is thought to be the first of its kind in the U.S. London, meanwhile, has handed out "Baby on Board" buttons to pregnant riders since 2005. The pin was popularized by—who else?—the Duchess of Cambridge, the former Kate Middleton, when she wore one on the Tube in 2013. The London transit system distributes about 130,000 buttons every year.
The pilot program in NYC, which began on Mother's Day and runs through Labor Day, could offer relief to pregnant subway riders who often face the uncomfortable choice of enduring a standing commute or awkwardly asking a sitting passenger for a seat. The ubiquity of smartphones means pregnant women in need of seats are often ignored as fellow riders are transfixed by their devices.
One pregnant New Yorker grew so frustrated with being forced to stand that she carried around a small trophy on the off chance a fellow rider offered her a seat. Yvonne Lin had completed nearly two entire pregnancies before a male passenger gave up his seat for her. (She'd received plenty of offers from women.) When a man forfeited his seat to Lin on the A train in February, she handed him the prize that read “#1 DECENT DUDE.”
A version of this story first appeared in Fortune's World's Most Powerful Women newsletter. Subscribe here.